diff --git a/modules/activiti-engine/src/main/java/org/activiti/engine/impl/ExecutionQueryImpl.java b/modules/activiti-engine/src/main/java/org/activiti/engine/impl/ExecutionQueryImpl.java
index 2e4bcd831dd959ebc6e2ba32a60fb9a110f1dbb8..6d3c1e970d058ea5711c0c07263f31571c3c0a1b 100644
--- a/modules/activiti-engine/src/main/java/org/activiti/engine/impl/ExecutionQueryImpl.java
+++ b/modules/activiti-engine/src/main/java/org/activiti/engine/impl/ExecutionQueryImpl.java
@@ -41,6 +41,7 @@ public class ExecutionQueryImpl extends ExecutionVariableQueryImpl<ExecutionQuer
   protected String superProcessInstanceId;
   protected String subProcessInstanceId;
   protected SuspensionState suspensionState;
+  private String businessKey;
   
   public ExecutionQueryImpl() {
   }
@@ -81,6 +82,14 @@ public class ExecutionQueryImpl extends ExecutionVariableQueryImpl<ExecutionQuer
     return this;
   }
   
+  public ExecutionQuery processInstanceBusinessKey(String businessKey) {
+    if (businessKey == null) {
+      throw new ActivitiException("Business key is null");
+    }
+    this.businessKey = businessKey;
+    return this;
+  }
+  
   public ExecutionQueryImpl executionId(String executionId) {
     if (executionId == null) {
       throw new ActivitiException("Execution id is null");
@@ -152,7 +161,7 @@ public class ExecutionQueryImpl extends ExecutionVariableQueryImpl<ExecutionQuer
     return null;
   }
   public String getBusinessKey() {
-    return null;
+    return businessKey;
   }
   public String getExecutionId() {
     return executionId;
diff --git a/modules/activiti-engine/src/main/java/org/activiti/engine/impl/TaskQueryImpl.java b/modules/activiti-engine/src/main/java/org/activiti/engine/impl/TaskQueryImpl.java
index 475faac8739653c396ccc18ae2821f6ceabec999..12b7c051b9e19deb55c8468af948a3404c8a021b 100644
--- a/modules/activiti-engine/src/main/java/org/activiti/engine/impl/TaskQueryImpl.java
+++ b/modules/activiti-engine/src/main/java/org/activiti/engine/impl/TaskQueryImpl.java
@@ -58,6 +58,7 @@ public class TaskQueryImpl extends AbstractQuery<TaskQuery, Task> implements Tas
   protected String processDefinitionKey;
   protected String processDefinitionId;
   protected String processDefinitionName;
+  protected String processInstanceBusinessKey;
   protected List<TaskQueryVariableValue> variables = new ArrayList<TaskQueryVariableValue>();
   protected Date dueDate;
   protected Date dueBefore;
@@ -216,6 +217,11 @@ public class TaskQueryImpl extends AbstractQuery<TaskQuery, Task> implements Tas
     return this;
   }
   
+  public TaskQueryImpl processInstanceBusinessKey(String processInstanceBusinessKey) {
+    this.processInstanceBusinessKey = processInstanceBusinessKey;
+    return this;
+  }
+  
   public TaskQueryImpl executionId(String executionId) {
     this.executionId = executionId;
     return this;
@@ -437,4 +443,9 @@ public class TaskQueryImpl extends AbstractQuery<TaskQuery, Task> implements Tas
   public String getProcessDefinitionName() {
     return processDefinitionName;
   }
+
+  
+  public String getProcessInstanceBusinessKey() {
+    return processInstanceBusinessKey;
+  }
 }
diff --git a/modules/activiti-engine/src/main/java/org/activiti/engine/runtime/ExecutionQuery.java b/modules/activiti-engine/src/main/java/org/activiti/engine/runtime/ExecutionQuery.java
index 45cfa71e819913ae935a5d4448783670e788dfdc..ec337b1cc293e02a7f05d576ebe64ec163cc1c21 100644
--- a/modules/activiti-engine/src/main/java/org/activiti/engine/runtime/ExecutionQuery.java
+++ b/modules/activiti-engine/src/main/java/org/activiti/engine/runtime/ExecutionQuery.java
@@ -35,6 +35,9 @@ public interface ExecutionQuery extends Query<ExecutionQuery, Execution>{
   /** Only select executions which have the given process instance id. **/
   ExecutionQuery processInstanceId(String processInstanceId);
   
+  /** Only executions with the given business key */
+  ExecutionQuery processInstanceBusinessKey(String processInstanceBusinessKey);
+
   /** Only select executions with the given id. **/
   ExecutionQuery executionId(String executionId);
   
diff --git a/modules/activiti-engine/src/main/java/org/activiti/engine/task/TaskQuery.java b/modules/activiti-engine/src/main/java/org/activiti/engine/task/TaskQuery.java
index 44f91dad01a9c57942b80272b9b48b47935d7d91..51ee2ee9ea1737bf76dc572e6e0eb7268e553312 100644
--- a/modules/activiti-engine/src/main/java/org/activiti/engine/task/TaskQuery.java
+++ b/modules/activiti-engine/src/main/java/org/activiti/engine/task/TaskQuery.java
@@ -84,6 +84,9 @@ public interface TaskQuery extends Query<TaskQuery, Task>{
 
   /** Only select tasks for the given process instance id. */
   TaskQuery processInstanceId(String processInstanceId);
+  
+  /** Only select tasks foe the given business key */
+  TaskQuery processInstanceBusinessKey(String processInstanceBusinessKey);  
 
   /** Only select tasks for the given execution. */
   TaskQuery executionId(String executionId);
diff --git a/modules/activiti-engine/src/main/resources/org/activiti/db/mapping/entity/Task.xml b/modules/activiti-engine/src/main/resources/org/activiti/db/mapping/entity/Task.xml
index 577be0779f26b3d7cd4ea81966018fa7948e0d3d..f76f4e68fe79ce7f04479d3a32b9aefd5f3c58eb 100644
--- a/modules/activiti-engine/src/main/resources/org/activiti/db/mapping/entity/Task.xml
+++ b/modules/activiti-engine/src/main/resources/org/activiti/db/mapping/entity/Task.xml
@@ -138,7 +138,10 @@
     <if test="processDefinitionKey != null || processDefinitionName != null">
       inner join ACT_RE_PROCDEF D on T.PROC_DEF_ID_ = D.ID_
     </if>
-    <where>
+    <if test="processInstanceBusinessKey != null">
+        inner join ACT_RU_EXECUTION E on T.PROC_INST_ID_ = E.ID_
+    </if>
+    <where> 
       <if test="taskId != null">
         T.ID_ = #{taskId}
       </if>
@@ -175,6 +178,9 @@
       <if test="processInstanceId != null">
         and T.PROC_INST_ID_ = #{processInstanceId}
       </if>
+      <if test="processInstanceBusinessKey != null">
+        and E.BUSINESS_KEY_ = #{processInstanceBusinessKey}
+      </if>         
       <if test="executionId != null">
         and T.EXECUTION_ID_ = #{executionId}
       </if>
diff --git a/modules/activiti-engine/src/test/java/org/activiti/engine/test/api/runtime/ExecutionQueryTest.java b/modules/activiti-engine/src/test/java/org/activiti/engine/test/api/runtime/ExecutionQueryTest.java
index b6e4a46c68fd11a1e987c180acdc137ec8a4d4a3..96e558bdd0f2c1b7b8cbe05e4b03fbd6b691026d 100644
--- a/modules/activiti-engine/src/test/java/org/activiti/engine/test/api/runtime/ExecutionQueryTest.java
+++ b/modules/activiti-engine/src/test/java/org/activiti/engine/test/api/runtime/ExecutionQueryTest.java
@@ -68,7 +68,7 @@ public class ExecutionQueryTest extends PluggableActivitiTestCase {
     sequentialProcessInstanceIds = new ArrayList<String>();
     
     for (int i = 0; i < 4; i++) {
-      concurrentProcessInstanceIds.add(runtimeService.startProcessInstanceByKey(CONCURRENT_PROCESS_KEY).getId());
+      concurrentProcessInstanceIds.add(runtimeService.startProcessInstanceByKey(CONCURRENT_PROCESS_KEY, "BUSINESS-KEY-" + i).getId());
     }
     sequentialProcessInstanceIds.add(runtimeService.startProcessInstanceByKey(SEQUENTIAL_PROCESS_KEY).getId());
   }
@@ -172,6 +172,12 @@ public class ExecutionQueryTest extends PluggableActivitiTestCase {
     }
   }
   
+  public void testQueryByBusinessKey() {
+    assertEquals(1, runtimeService.createExecutionQuery().processDefinitionKey(CONCURRENT_PROCESS_KEY).processInstanceBusinessKey("BUSINESS-KEY-1").list().size());
+    assertEquals(1, runtimeService.createExecutionQuery().processDefinitionKey(CONCURRENT_PROCESS_KEY).processInstanceBusinessKey("BUSINESS-KEY-2").list().size());
+    assertEquals(0, runtimeService.createExecutionQuery().processDefinitionKey(CONCURRENT_PROCESS_KEY).processInstanceBusinessKey("NON-EXISTING").list().size());
+  }  
+  
   @Deployment(resources={
     "org/activiti/engine/test/api/oneTaskProcess.bpmn20.xml"})
   public void testQueryStringVariable() {
diff --git a/modules/activiti-engine/src/test/java/org/activiti/engine/test/api/task/TaskQueryTest.java b/modules/activiti-engine/src/test/java/org/activiti/engine/test/api/task/TaskQueryTest.java
index 3166278b422ec3bdcb738e1cb5d0225f6d02d684..1952faf516bce7e659f765a3160fede7adedd1c9 100644
--- a/modules/activiti-engine/src/test/java/org/activiti/engine/test/api/task/TaskQueryTest.java
+++ b/modules/activiti-engine/src/test/java/org/activiti/engine/test/api/task/TaskQueryTest.java
@@ -577,7 +577,16 @@ public class TaskQueryTest extends PluggableActivitiTestCase {
     
     assertEquals(0, taskService.createTaskQuery().processDefinitionName("unexisting").count());
   }
-  
+ 
+  @Deployment(resources={"org/activiti/engine/test/api/task/TaskQueryTest.testProcessDefinition.bpmn20.xml"})
+  public void testProcessInstanceBusinessKey() throws Exception {
+    ProcessInstance processInstance = runtimeService.startProcessInstanceByKey("oneTaskProcess", "BUSINESS-KEY-1");
+    
+    assertEquals(1, taskService.createTaskQuery().processDefinitionName("The One Task Process").processInstanceBusinessKey("BUSINESS-KEY-1").list().size());
+    assertEquals(1, taskService.createTaskQuery().processInstanceBusinessKey("BUSINESS-KEY-1").list().size());    
+    assertEquals(0, taskService.createTaskQuery().processInstanceBusinessKey("NON-EXISTING").count());
+  }
+ 
   @Deployment(resources={"org/activiti/engine/test/api/task/TaskQueryTest.testProcessDefinition.bpmn20.xml"})
   public void testTaskDueDate() throws Exception {
     ProcessInstance processInstance = runtimeService.startProcessInstanceByKey("oneTaskProcess");