diff --git a/internal/internal_task_handlers.go b/internal/internal_task_handlers.go
index 831258776..10c20ee09 100644
--- a/internal/internal_task_handlers.go
+++ b/internal/internal_task_handlers.go
@@ -32,6 +32,7 @@ import (
 	"fmt"
 	"math"
 	"reflect"
+	"strconv"
 	"strings"
 	"sync"
 	"time"
@@ -1023,6 +1024,8 @@ func (w *workflowExecutionContextImpl) ProcessWorkflowTask(workflowTask *workflo
 		return !wfPanicked && isInReplayer
 	}
 
+	var wftCompletedIndex int64
+
 	metricsHandler := w.wth.metricsHandler.WithTags(metrics.WorkflowTags(task.WorkflowType.GetName()))
 	start := time.Now()
 	// This is set to nil once recorded
@@ -1045,10 +1048,26 @@ ProcessEvents:
 		binaryChecksum := nextTask.binaryChecksum
 		nextTaskBuildId := nextTask.buildID
 		admittedUpdates := nextTask.admittedMsgs
+		// Only replay up to the last completed event
+		if len(reorderedEvents) > 0 {
+			if reorderedEvents[len(reorderedEvents)-1].GetEventType() == enumspb.EVENT_TYPE_WORKFLOW_TASK_STARTED {
+				wftCompletedIndex = reorderedEvents[len(reorderedEvents)-2].EventId
+			} else if reorderedEvents[len(reorderedEvents)-1].GetEventType() == enumspb.EVENT_TYPE_WORKFLOW_TASK_COMPLETED || reorderedEvents[len(reorderedEvents)-1].GetEventType() == enumspb.EVENT_TYPE_ACTIVITY_TASK_COMPLETED {
+				wftCompletedIndex = reorderedEvents[len(reorderedEvents)-1].EventId
+			} else
+			// If completed + task scheduled, that's a WFT heartbeat, does not complete sequence
+			if (len(reorderedEvents) == 1 && reorderedEvents[0].GetEventType() == enumspb.EVENT_TYPE_WORKFLOW_TASK_COMPLETED) || (len(reorderedEvents) > 1 && reorderedEvents[0].GetEventType() == enumspb.EVENT_TYPE_WORKFLOW_TASK_COMPLETED && reorderedEvents[1].GetEventType() != enumspb.EVENT_TYPE_WORKFLOW_TASK_SCHEDULED) {
+				wftCompletedIndex = reorderedEvents[0].EventId
+			}
+		}
+
 		// Check if we are replaying so we know if we should use the messages in the WFT or the history
 		isReplay := len(reorderedEvents) > 0 && reorderedHistory.IsReplayEvent(reorderedEvents[len(reorderedEvents)-1])
 		var msgs *eventMsgIndex
 		if isReplay {
+			//if reorderedEvents[0].GetEventType() == enumspb.EVENT_TYPE_WORKFLOW_TASK_COMPLETED {
+			//	completedTaskReplayCommandIndex = len(replayCommands)
+			//}
 			admittedUpdatesByID := make(map[string]*protocolpb.Message, len(admittedUpdates))
 			for _, admittedUpdate := range admittedUpdates {
 				admittedUpdatesByID[admittedUpdate.GetProtocolInstanceId()] = admittedUpdate
@@ -1181,6 +1200,9 @@ ProcessEvents:
 			}
 		}
 		if isReplay {
+			// TODO: Why does this have commands that aren't a part of history?
+			//  looks like both replayCommands and respondEvents sometimes hold events/commands that aren't a part of
+			//  the replay history
 			eventCommands := eventHandler.commandsHelper.getCommands(true)
 			if !skipReplayCheck {
 				replayCommands = append(replayCommands, eventCommands...)
@@ -1195,6 +1217,23 @@ ProcessEvents:
 		metricsTimer = nil
 	}
 
+	// We do not want to run non-determinism checks on a task start that
+	// doesn't have a corresponding completed task.
+	for i, cmd := range replayCommands {
+		activityId, err := strconv.ParseInt(cmd.GetScheduleActivityTaskCommandAttributes().ActivityId, 10, 64)
+		if err != nil {
+			return nil, err
+		}
+		if activityId > wftCompletedIndex {
+			replayCommands = replayCommands[:i]
+		}
+	}
+	for i, event := range respondEvents {
+		if event.EventId > wftCompletedIndex {
+			respondEvents = respondEvents[:i]
+		}
+	}
+
 	// Non-deterministic error could happen in 2 different places:
 	//   1) the replay commands does not match to history events. This is usually due to non backwards compatible code
 	// change to workflow logic. For example, change calling one activity to a different activity.
@@ -2339,3 +2378,14 @@ func traceLog(fn func()) {
 		fn()
 	}
 }
+
+//func trimEventsToCompletedWFT(commands []*commandpb.Command) []*commandpb.Command {
+//	lastIndex := 0
+//	sawAnyCommandEvent := false
+//	// wftStartedEventIdToIndex
+//	for ix, command := range commands {
+//		last_index := ix
+//
+//		if
+//	}
+//}
diff --git a/internal/internal_worker_test.go b/internal/internal_worker_test.go
index 6a5a34862..2859d4614 100644
--- a/internal/internal_worker_test.go
+++ b/internal/internal_worker_test.go
@@ -314,6 +314,27 @@ func (s *internalWorkerTestSuite) TestReplayWorkflowHistory() {
 	require.NoError(s.T(), err)
 }
 
+func (s *internalWorkerTestSuite) TestReplayWorkflowHistory_IncompleteWorkflowTask() {
+	taskQueue := "taskQueue1"
+	testEvents := []*historypb.HistoryEvent{
+		createTestEventWorkflowExecutionStarted(1, &historypb.WorkflowExecutionStartedEventAttributes{
+			WorkflowType: &commonpb.WorkflowType{Name: "testReplayWorkflow"},
+			TaskQueue:    &taskqueuepb.TaskQueue{Name: taskQueue},
+			Input:        testEncodeFunctionArgs(converter.GetDefaultDataConverter()),
+		}),
+		createTestEventWorkflowTaskScheduled(2, &historypb.WorkflowTaskScheduledEventAttributes{}),
+		createTestEventWorkflowTaskStarted(3),
+	}
+
+	history := &historypb.History{Events: testEvents}
+	logger := getLogger()
+	replayer, err := NewWorkflowReplayer(WorkflowReplayerOptions{})
+	require.NoError(s.T(), err)
+	replayer.RegisterWorkflow(testReplayWorkflow)
+	err = replayer.ReplayWorkflowHistory(logger, history)
+	require.NoError(s.T(), err)
+}
+
 func (s *internalWorkerTestSuite) TestReplayWorkflowHistory_LocalActivity() {
 	taskQueue := "taskQueue1"
 	testEvents := []*historypb.HistoryEvent{
diff --git a/test/integration_test.go b/test/integration_test.go
index bafe9667a..17c8723f8 100644
--- a/test/integration_test.go
+++ b/test/integration_test.go
@@ -6904,3 +6904,38 @@ func (ts *InvalidUTF8Suite) TestBasic() {
 	// Go's JSON coding stack will replace invalid bytes with the unicode substitute char U+FFFD
 	ts.Equal("\n�\x01\n\x0ejunk\x12data", response)
 }
+
+func (ts *IntegrationTestSuite) TestPartialHistoryReplay() {
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	// Run the workflow
+	run, err := ts.client.ExecuteWorkflow(ctx,
+		ts.startWorkflowOptions("test-partial-history-replay"), ts.workflows.Basic)
+	ts.NotNil(run)
+	ts.NoError(err)
+	ts.NoError(run.Get(ctx, nil))
+
+	// Obtain history
+	var history historypb.History
+	iter := ts.client.GetWorkflowHistory(ctx, run.GetID(), run.GetRunID(), false,
+		enumspb.HISTORY_EVENT_FILTER_TYPE_ALL_EVENT)
+	for iter.HasNext() {
+		event, err := iter.Next()
+		ts.NoError(err)
+		history.Events = append(history.Events, event)
+	}
+
+	for _ = range history.Events {
+		if len(history.Events) >= 3 {
+			fmt.Println("\n[REPLAY]")
+			for i, event := range history.Events {
+				fmt.Println("\t[event],", i, event)
+			}
+			replayer := worker.NewWorkflowReplayer()
+			replayer.RegisterWorkflow(ts.workflows.Basic)
+			ts.NoError(replayer.ReplayWorkflowHistory(nil, &history))
+			history.Events = history.Events[:len(history.Events)-1]
+		}
+	}
+}