diff --git a/lib/Doctrine/ORM/Query/SqlWalker.php b/lib/Doctrine/ORM/Query/SqlWalker.php
index 57287c7cb..62350c389 100644
--- a/lib/Doctrine/ORM/Query/SqlWalker.php
+++ b/lib/Doctrine/ORM/Query/SqlWalker.php
@@ -2038,8 +2038,10 @@ class SqlWalker implements TreeWalker
 
         $sql .= $class->discriminatorColumn['name'] . ($instanceOfExpr->not ? ' NOT IN ' : ' IN ');
 
-        $sqlParameterList = [];
+        $knownSubclasses = array_flip($discrClass->subClasses);
 
+        $sqlParameterList = [];
+        $discriminators = [];
         foreach ($instanceOfExpr->value as $parameter) {
             if ($parameter instanceof AST\InputParameter) {
                 $this->rsm->addMetadataParameterMapping($parameter->name, 'discriminatorValue');
@@ -2049,21 +2051,31 @@ class SqlWalker implements TreeWalker
                 continue;
             }
 
-            // Get name from ClassMetadata to resolve aliases.
-            $entityClassName    = $this->em->getClassMetadata($parameter)->name;
-            $discriminatorValue = $class->discriminatorValue;
+            // Trim first backslash
+            $parameter = ltrim($parameter, '\\');
 
-            if ($entityClassName !== $class->name) {
-                $discrMap = array_flip($class->discriminatorMap);
-
-                if ( ! isset($discrMap[$entityClassName])) {
-                    throw QueryException::instanceOfUnrelatedClass($entityClassName, $class->rootEntityName);
-                }
-
-                $discriminatorValue = $discrMap[$entityClassName];
+            // Check parameter is really in the hierarchy
+            if ($parameter !== $discrClass->name && ! array_key_exists($parameter, $knownSubclasses)) {
+                throw QueryException::instanceOfUnrelatedClass($parameter, $discrClass->name);
             }
 
-            $sqlParameterList[] = $this->conn->quote($discriminatorValue);
+            // Include discriminators for parameter class and its subclass
+            $metadata = $this->em->getClassMetadata($parameter);
+            $hierarchyClasses = $metadata->subClasses;
+            $hierarchyClasses[] = $metadata->name;
+
+            foreach ($hierarchyClasses as $class) {
+                $currentMetadata = $this->em->getClassMetadata($class);
+                $currentDiscriminator = $currentMetadata->discriminatorValue;
+
+                if (is_string($currentDiscriminator) && ! array_key_exists($currentDiscriminator, $discriminators)) {
+                    $discriminators[$currentDiscriminator] = true;
+                }
+            }
+        }
+
+        foreach (array_keys($discriminators) as $dis) {
+            $sqlParameterList[] = $this->conn->quote($dis);
         }
 
         $sql .= '(' . implode(', ', $sqlParameterList) . ')';
diff --git a/tests/Doctrine/Tests/ORM/Functional/InstanceOfAbstractTest.php b/tests/Doctrine/Tests/ORM/Functional/InstanceOfAbstractTest.php
new file mode 100644
index 000000000..a84643f84
--- /dev/null
+++ b/tests/Doctrine/Tests/ORM/Functional/InstanceOfAbstractTest.php
@@ -0,0 +1,113 @@
+<?php
+
+namespace Doctrine\Tests\ORM\Functional {
+
+    use Doctrine\Tests\OrmFunctionalTestCase;
+
+    class InstanceOfAbstractTest extends OrmFunctionalTestCase
+    {
+        protected function setUp()
+        {
+            parent::setUp();
+
+            $this->_schemaTool->createSchema(array(
+                $this->_em->getClassMetadata(__NAMESPACE__ . '\InstanceOfAbstractTest\Person'),
+                $this->_em->getClassMetadata(__NAMESPACE__ . '\InstanceOfAbstractTest\Employee'),
+            ));
+        }
+
+        public function testInstanceOf()
+        {
+            $this->loadData();
+
+            $dql = 'SELECT p FROM Doctrine\Tests\ORM\Functional\InstanceOfAbstractTest\Person p
+                    WHERE p INSTANCE OF Doctrine\Tests\ORM\Functional\InstanceOfAbstractTest\Person';
+            $query = $this->_em->createQuery($dql);
+            $result = $query->getResult();
+
+            $this->assertCount(1, $result);
+
+            foreach ($result as $r) {
+                $this->assertInstanceOf('Doctrine\Tests\ORM\Functional\InstanceOfAbstractTest\Person', $r);
+                $this->assertInstanceOf('Doctrine\Tests\ORM\Functional\InstanceOfAbstractTest\Employee', $r);
+                $this->assertEquals('bar', $r->getName());
+            }
+        }
+
+        private function loadData()
+        {
+            $employee = new InstanceOfAbstractTest\Employee();
+            $employee->setName('bar');
+            $employee->setDepartement('qux');
+
+            $this->_em->persist($employee);
+
+            $this->_em->flush($employee);
+        }
+    }
+}
+
+namespace Doctrine\Tests\ORM\Functional\InstanceOfAbstractTest {
+
+    /**
+     * @Entity()
+     * @Table(name="instance_of_abstract_test_person")
+     * @InheritanceType(value="JOINED")
+     * @DiscriminatorColumn(name="kind", type="string")
+     * @DiscriminatorMap(value={
+     *     "employee": "Doctrine\Tests\ORM\Functional\InstanceOfAbstractTest\Employee"
+     * })
+     */
+    abstract class Person
+    {
+        /**
+         * @Id()
+         * @GeneratedValue()
+         * @Column(type="integer")
+         */
+        private $id;
+
+        /**
+         * @Column(type="string")
+         */
+        private $name;
+
+        public function getId()
+        {
+            return $this->id;
+        }
+
+        public function getName()
+        {
+            return $this->name;
+        }
+
+        public function setName($name)
+        {
+            $this->name = $name;
+        }
+    }
+
+    /**
+     * @Entity()
+     * @Table(name="instance_of_abstract_test_employee")
+     */
+    class Employee extends Person
+    {
+        /**
+         * @Column(type="string")
+         */
+        private $departement;
+
+        public function getDepartement()
+        {
+            return $this->departement;
+        }
+
+        public function setDepartement($departement)
+        {
+            $this->departement = $departement;
+        }
+    }
+
+}
diff --git a/tests/Doctrine/Tests/ORM/Functional/InstanceOfMultiLevelTest.php b/tests/Doctrine/Tests/ORM/Functional/InstanceOfMultiLevelTest.php
new file mode 100644
index 000000000..c4b5bbcd2
--- /dev/null
+++ b/tests/Doctrine/Tests/ORM/Functional/InstanceOfMultiLevelTest.php
@@ -0,0 +1,153 @@
+<?php
+
+namespace Doctrine\Tests\ORM\Functional {
+
+    use Doctrine\Tests\OrmFunctionalTestCase;
+
+    class InstanceOfMultiLevelTest extends OrmFunctionalTestCase
+    {
+        protected function setUp()
+        {
+            parent::setUp();
+
+            $this->_schemaTool->createSchema(array(
+                $this->_em->getClassMetadata(__NAMESPACE__ . '\InstanceOfMultiLevelTest\Person'),
+                $this->_em->getClassMetadata(__NAMESPACE__ . '\InstanceOfMultiLevelTest\Employee'),
+                $this->_em->getClassMetadata(__NAMESPACE__ . '\InstanceOfMultiLevelTest\Engineer'),
+            ));
+        }
+
+        public function testInstanceOf()
+        {
+            $this->loadData();
+
+            $dql = 'SELECT p FROM Doctrine\Tests\ORM\Functional\InstanceOfMultiLevelTest\Person p
+                    WHERE p INSTANCE OF Doctrine\Tests\ORM\Functional\InstanceOfMultiLevelTest\Person';
+            $query = $this->_em->createQuery($dql);
+            $result = $query->getResult();
+
+            $this->assertCount(3, $result);
+
+            foreach ($result as $r) {
+                $this->assertInstanceOf('Doctrine\Tests\ORM\Functional\InstanceOfMultiLevelTest\Person', $r);
+                if ($r instanceof InstanceOfMultiLevelTest\Engineer) {
+                    $this->assertEquals('foobar', $r->getName());
+                    $this->assertEquals('doctrine', $r->getSpecialization());
+                } elseif ($r instanceof InstanceOfMultiLevelTest\Employee) {
+                    $this->assertEquals('bar', $r->getName());
+                    $this->assertEquals('qux', $r->getDepartement());
+                } else {
+                    $this->assertEquals('foo', $r->getName());
+                }
+            }
+        }
+
+        private function loadData()
+        {
+            $person = new InstanceOfMultiLevelTest\Person();
+            $person->setName('foo');
+
+            $employee = new InstanceOfMultiLevelTest\Employee();
+            $employee->setName('bar');
+            $employee->setDepartement('qux');
+
+            $engineer = new InstanceOfMultiLevelTest\Engineer();
+            $engineer->setName('foobar');
+            $engineer->setDepartement('dep');
+            $engineer->setSpecialization('doctrine');
+
+            $this->_em->persist($person);
+            $this->_em->persist($employee);
+            $this->_em->persist($engineer);
+
+            $this->_em->flush(array($person, $employee, $engineer));
+        }
+    }
+}
+
+namespace Doctrine\Tests\ORM\Functional\InstanceOfMultiLevelTest {
+    /**
+     * @Entity()
+     * @Table(name="instance_of_multi_level_test_person")
+     * @InheritanceType(value="JOINED")
+     * @DiscriminatorColumn(name="kind", type="string")
+     * @DiscriminatorMap(value={
+     *     "person": "Doctrine\Tests\ORM\Functional\InstanceOfMultiLevelTest\Person",
+     *     "employee": "Doctrine\Tests\ORM\Functional\InstanceOfMultiLevelTest\Employee",
+     *     "engineer": "Doctrine\Tests\ORM\Functional\InstanceOfMultiLevelTest\Engineer",
+     * })
+     */
+    class Person
+    {
+        /**
+         * @Id()
+         * @GeneratedValue()
+         * @Column(type="integer")
+         */
+        private $id;
+
+        /**
+         * @Column(type="string")
+         */
+        private $name;
+
+        public function getId()
+        {
+            return $this->id;
+        }
+
+        public function getName()
+        {
+            return $this->name;
+        }
+
+        public function setName($name)
+        {
+            $this->name = $name;
+        }
+    }
+
+    /**
+     * @Entity()
+     * @Table(name="instance_of_multi_level_employee")
+     */
+    class Employee extends Person
+    {
+        /**
+         * @Column(type="string")
+         */
+        private $departement;
+
+        public function getDepartement()
+        {
+            return $this->departement;
+        }
+
+        public function setDepartement($departement)
+        {
+            $this->departement = $departement;
+        }
+    }
+
+    /**
+     * @Entity()
+     * @Table(name="instance_of_multi_level_engineer")
+     */
+    class Engineer extends Employee
+    {
+        /**
+         * @Column(type="string")
+         */
+        private $specialization;
+
+        public function getSpecialization()
+        {
+            return $this->specialization;
+        }
+
+        public function setSpecialization($specialization)
+        {
+            $this->specialization = $specialization;
+        }
+    }
+}
diff --git a/tests/Doctrine/Tests/ORM/Functional/InstanceOfTest.php b/tests/Doctrine/Tests/ORM/Functional/InstanceOfTest.php
new file mode 100644
index 000000000..7f593c3f4
--- /dev/null
+++ b/tests/Doctrine/Tests/ORM/Functional/InstanceOfTest.php
@@ -0,0 +1,119 @@
+<?php
+
+namespace Doctrine\Tests\ORM\Functional {
+
+    use Doctrine\Tests\OrmFunctionalTestCase;
+
+    class InstanceOfTest extends OrmFunctionalTestCase
+    {
+        protected function setUp()
+        {
+            parent::setUp();
+
+            $this->_schemaTool->createSchema(array(
+                $this->_em->getClassMetadata(__NAMESPACE__ . '\InstanceOfTest\Person'),
+                $this->_em->getClassMetadata(__NAMESPACE__ . '\InstanceOfTest\Employee'),
+            ));
+        }
+
+        public function testInstanceOf()
+        {
+            $this->loadData();
+
+            $dql = 'SELECT p FROM Doctrine\Tests\ORM\Functional\InstanceOfTest\Person p
+                    WHERE p INSTANCE OF Doctrine\Tests\ORM\Functional\InstanceOfTest\Person';
+            $query = $this->_em->createQuery($dql);
+            $result = $query->getResult();
+
+            $this->assertCount(2, $result);
+
+            foreach ($result as $r) {
+                $this->assertInstanceOf('Doctrine\Tests\ORM\Functional\InstanceOfTest\Person', $r);
+                if ($r instanceof InstanceOfTest\Employee) {
+                    $this->assertEquals('bar', $r->getName());
+                } else {
+                    $this->assertEquals('foo', $r->getName());
+                }
+            }
+        }
+
+        private function loadData()
+        {
+            $person = new InstanceOfTest\Person();
+            $person->setName('foo');
+
+            $employee = new InstanceOfTest\Employee();
+            $employee->setName('bar');
+            $employee->setDepartement('qux');
+
+            $this->_em->persist($person);
+            $this->_em->persist($employee);
+
+            $this->_em->flush(array($person, $employee));
+        }
+    }
+}
+
+namespace Doctrine\Tests\ORM\Functional\InstanceOfTest {
+    /**
+     * @Entity()
+     * @Table(name="instance_of_test_person")
+     * @InheritanceType(value="JOINED")
+     * @DiscriminatorColumn(name="kind", type="string")
+     * @DiscriminatorMap(value={
+     *     "person": "Doctrine\Tests\ORM\Functional\InstanceOfTest\Person",
+     *     "employee": "Doctrine\Tests\ORM\Functional\InstanceOfTest\Employee"
+     * })
+     */
+    class Person
+    {
+        /**
+         * @Id()
+         * @GeneratedValue()
+         * @Column(type="integer")
+         */
+        private $id;
+
+        /**
+         * @Column(type="string")
+         */
+        private $name;
+
+        public function getId()
+        {
+            return $this->id;
+        }
+
+        public function getName()
+        {
+            return $this->name;
+        }
+
+        public function setName($name)
+        {
+            $this->name = $name;
+        }
+    }
+
+    /**
+     * @Entity()
+     * @Table(name="instance_of_test_employee")
+     */
+    class Employee extends Person
+    {
+        /**
+         * @Column(type="string")
+         */
+        private $departement;
+
+        public function getDepartement()
+        {
+            return $this->departement;
+        }
+
+        public function setDepartement($departement)
+        {
+            $this->departement = $departement;
+        }
+    }
+}
diff --git a/tests/Doctrine/Tests/ORM/Query/SelectSqlGenerationTest.php b/tests/Doctrine/Tests/ORM/Query/SelectSqlGenerationTest.php
index b6bdce323..f9fb0b820 100644
--- a/tests/Doctrine/Tests/ORM/Query/SelectSqlGenerationTest.php
+++ b/tests/Doctrine/Tests/ORM/Query/SelectSqlGenerationTest.php
@@ -502,7 +502,7 @@ class SelectSqlGenerationTest extends OrmTestCase
     {
         $this->assertSqlGeneration(
             "SELECT u FROM Doctrine\Tests\Models\Company\CompanyPerson u WHERE u INSTANCE OF Doctrine\Tests\Models\Company\CompanyEmployee",
-            "SELECT c0_.id AS id_0, c0_.name AS name_1, c0_.discr AS discr_2 FROM company_persons c0_ WHERE c0_.discr IN ('employee')"
+            "SELECT c0_.id AS id_0, c0_.name AS name_1, c0_.discr AS discr_2 FROM company_persons c0_ WHERE c0_.discr IN ('manager', 'employee')"
         );
     }
 
@@ -511,7 +511,7 @@ class SelectSqlGenerationTest extends OrmTestCase
         // This also uses FQCNs starting with or without a backslash in the INSTANCE OF parameter
         $this->assertSqlGeneration(
             "SELECT u FROM Doctrine\Tests\Models\Company\CompanyPerson u WHERE u INSTANCE OF (Doctrine\Tests\Models\Company\CompanyEmployee, \Doctrine\Tests\Models\Company\CompanyManager)",
-            "SELECT c0_.id AS id_0, c0_.name AS name_1, c0_.discr AS discr_2 FROM company_persons c0_ WHERE c0_.discr IN ('employee', 'manager')"
+            "SELECT c0_.id AS id_0, c0_.name AS name_1, c0_.discr AS discr_2 FROM company_persons c0_ WHERE c0_.discr IN ('manager', 'employee')"
         );
     }
 
@@ -522,7 +522,7 @@ class SelectSqlGenerationTest extends OrmTestCase
     {
         $this->assertSqlGeneration(
             "SELECT u FROM Doctrine\Tests\Models\Company\CompanyPerson u WHERE u INSTANCE OF \Doctrine\Tests\Models\Company\CompanyEmployee",
-            "SELECT c0_.id AS id_0, c0_.name AS name_1, c0_.discr AS discr_2 FROM company_persons c0_ WHERE c0_.discr IN ('employee')"
+            "SELECT c0_.id AS id_0, c0_.name AS name_1, c0_.discr AS discr_2 FROM company_persons c0_ WHERE c0_.discr IN ('manager', 'employee')"
         );
     }