diff --git a/AcceptanceTests/NServiceBus.AcceptanceTests/NServiceBus.AcceptanceTests.csproj b/AcceptanceTests/NServiceBus.AcceptanceTests/NServiceBus.AcceptanceTests.csproj
index c7d2d69043..6d2b87e5b8 100644
--- a/AcceptanceTests/NServiceBus.AcceptanceTests/NServiceBus.AcceptanceTests.csproj
+++ b/AcceptanceTests/NServiceBus.AcceptanceTests/NServiceBus.AcceptanceTests.csproj
@@ -173,6 +173,7 @@
     <Compile Include="Retries\When_messages_fails_flr.cs" />
     <Compile Include="Retries\When_message_fails_with_retries_set_to_0.cs" />
     <Compile Include="Retries\When_doing_flr_with_default_settings.cs" />
+    <Compile Include="Sagas\When_message_has_a_saga_id.cs" />
     <Compile Include="Sagas\When_doing_request_response_between_sagas.cs" />
     <Compile Include="Sagas\When_sending_from_a_saga_timeout.cs" />
     <Compile Include="Sagas\When_sending_from_a_saga_handle.cs" />
diff --git a/AcceptanceTests/NServiceBus.AcceptanceTests/Sagas/When_message_has_a_saga_id.cs b/AcceptanceTests/NServiceBus.AcceptanceTests/Sagas/When_message_has_a_saga_id.cs
new file mode 100644
index 0000000000..bc3ccb5a78
--- /dev/null
+++ b/AcceptanceTests/NServiceBus.AcceptanceTests/Sagas/When_message_has_a_saga_id.cs
@@ -0,0 +1,77 @@
+namespace NServiceBus.AcceptanceTests.Sagas
+{
+    using System;
+    using AcceptanceTesting;
+    using EndpointTemplates;
+    using Saga;
+    using NUnit.Framework;
+
+    public class When_message_has_a_saga_id : NServiceBusAcceptanceTest
+    {
+        [Test]
+        public void Should_not_start_a_new_saga_if_not_found()
+        {
+            var context = Scenario.Define<Context>()
+                .WithEndpoint<SagaEndpoint>(b => b.Given(bus =>
+                {
+                    var message = new MessageWithSagaId();
+
+                    bus.SetMessageHeader(message, Headers.SagaId, Guid.NewGuid().ToString());
+                    bus.SetMessageHeader(message, Headers.SagaType, typeof(MySaga).AssemblyQualifiedName);
+
+                    bus.SendLocal(message);
+                }))
+                .Done(c => c.NotFoundHandlerCalled)
+                .Run(TimeSpan.FromSeconds(15));
+
+            Assert.True(context.NotFoundHandlerCalled);
+            Assert.False(context.MessageHandlerCalled);
+            Assert.False(context.TimeoutHandlerCalled);
+        }
+
+        class MySaga : Saga<MySaga.SagaData>, IAmStartedByMessages<MessageWithSagaId>,
+            IHandleTimeouts<MessageWithSagaId>,
+            IHandleSagaNotFound
+        {
+            public Context Context { get; set; }
+
+            public class SagaData : ContainSagaData
+            {
+            }
+
+            public void Handle(MessageWithSagaId message)
+            {
+                Context.MessageHandlerCalled = true;
+            }
+
+            public void Handle(object message)
+            {
+                Context.NotFoundHandlerCalled = true;
+            }
+
+            public void Timeout(MessageWithSagaId state)
+            {
+                Context.TimeoutHandlerCalled = true;
+            }
+        }
+
+        class Context : ScenarioContext
+        {
+            public bool NotFoundHandlerCalled { get; set; }
+            public bool MessageHandlerCalled { get; set; }
+            public bool TimeoutHandlerCalled { get; set; }
+        }
+
+        public class SagaEndpoint : EndpointConfigurationBuilder
+        {
+            public SagaEndpoint()
+            {
+                EndpointSetup<DefaultServer>();
+            }
+        }
+
+        public class MessageWithSagaId : IMessage
+        {
+        }
+    }
+}
\ No newline at end of file
diff --git a/src/NServiceBus.Core/Sagas/SagaDispatcherFactory.cs b/src/NServiceBus.Core/Sagas/SagaDispatcherFactory.cs
index 02b8a7449d..f73b2fd912 100644
--- a/src/NServiceBus.Core/Sagas/SagaDispatcherFactory.cs
+++ b/src/NServiceBus.Core/Sagas/SagaDispatcherFactory.cs
@@ -44,6 +44,9 @@ public IEnumerable<Action> GetDispatcher(Type messageHandlerType, IBuilder build
                     if (sagaTypesHandled.Contains(sagaType))
                         continue; // don't create the same saga type twice for the same message
 
+                    if (!IsAllowedToStartANewSaga(sagaType))
+                        continue;
+
                     sagaEntity = CreateNewSagaEntity(sagaType);
 
                     sagaEntityIsPersistent = false;
@@ -128,6 +131,25 @@ public IEnumerable<Action> GetDispatcher(Type messageHandlerType, IBuilder build
                                  };
         }
 
+        bool IsAllowedToStartANewSaga(Type sagaInstanceType)
+        {
+            string sagaType;
+
+            if (Bus.CurrentMessageContext.Headers.ContainsKey(Headers.SagaId) &&
+                Bus.CurrentMessageContext.Headers.TryGetValue(Headers.SagaType, out sagaType))
+            {
+                //we want to move away from the assembly fully qualified name since that will break if you move sagas
+                // between assemblies. We use the fullname instead which is enough to identify the saga
+                if (sagaType.StartsWith(sagaInstanceType.FullName))
+                {
+                    //so now we have a saga id for this saga and if we can't find it we shouldn't start a new one
+                    return false;
+                }
+            }
+
+            return true;
+        }
+
         IContainSagaData CreateNewSagaEntity(Type sagaType)
         {
             var sagaEntityType = Features.Sagas.GetSagaEntityTypeForSagaType(sagaType);