diff --git a/exporters/otlp/internal/transform/span.go b/exporters/otlp/internal/transform/span.go
index 38a48bf1d..ca67527cb 100644
--- a/exporters/otlp/internal/transform/span.go
+++ b/exporters/otlp/internal/transform/span.go
@@ -65,10 +65,10 @@ func span(sd *export.SpanData) *tracepb.Span {
 	if sd == nil {
 		return nil
 	}
-	return &tracepb.Span{
+
+	s := &tracepb.Span{
 		TraceId:           sd.SpanContext.TraceID[:],
 		SpanId:            sd.SpanContext.SpanID[:],
-		ParentSpanId:      sd.ParentSpanID[:],
 		Status:            status(sd.StatusCode, sd.StatusMessage),
 		StartTimeUnixNano: uint64(sd.StartTime.UnixNano()),
 		EndTimeUnixNano:   uint64(sd.EndTime.UnixNano()),
@@ -82,6 +82,12 @@ func span(sd *export.SpanData) *tracepb.Span {
 		DroppedEventsCount:     uint32(sd.DroppedMessageEventCount),
 		DroppedLinksCount:      uint32(sd.DroppedLinkCount),
 	}
+
+	if sd.ParentSpanID.IsValid() {
+		s.ParentSpanId = sd.ParentSpanID[:]
+	}
+
+	return s
 }
 
 // status transform a span code and message into an OTLP span status.
diff --git a/exporters/otlp/internal/transform/span_test.go b/exporters/otlp/internal/transform/span_test.go
index eec4b3c2f..9525e3e25 100644
--- a/exporters/otlp/internal/transform/span_test.go
+++ b/exporters/otlp/internal/transform/span_test.go
@@ -360,3 +360,12 @@ func TestSpanData(t *testing.T) {
 		t.Fatalf("transformed span differs %v\n", diff)
 	}
 }
+
+// Empty parent span ID should be treated as root span.
+func TestRootSpanData(t *testing.T) {
+	rs := SpanData([]*export.SpanData{{}})[0]
+	got := rs.GetInstrumentationLibrarySpans()[0].GetSpans()[0].GetParentSpanId()
+
+	// Empty means root span.
+	assert.Nil(t, got, "incorrect transform of root parent span ID")
+}