diff --git a/spring-cloud-sleuth-reactor/src/main/java/org/springframework/cloud/sleuth/instrument/reactor/TraceReactorAutoConfiguration.java b/spring-cloud-sleuth-reactor/src/main/java/org/springframework/cloud/sleuth/instrument/reactor/TraceReactorAutoConfiguration.java
index 60ab0de42..2d98823a3 100644
--- a/spring-cloud-sleuth-reactor/src/main/java/org/springframework/cloud/sleuth/instrument/reactor/TraceReactorAutoConfiguration.java
+++ b/spring-cloud-sleuth-reactor/src/main/java/org/springframework/cloud/sleuth/instrument/reactor/TraceReactorAutoConfiguration.java
@@ -15,6 +15,8 @@ import org.springframework.cloud.sleuth.Tracer;
 import org.springframework.cloud.sleuth.autoconfig.TraceAutoConfiguration;
 import org.springframework.cloud.sleuth.instrument.async.TraceableScheduledExecutorService;
 import org.springframework.context.annotation.Configuration;
+
+import reactor.core.Fuseable;
 import reactor.core.publisher.Hooks;
 import reactor.core.publisher.Mono;
 import reactor.core.scheduler.Schedulers;
@@ -42,8 +44,15 @@ public class TraceReactorAutoConfiguration {
 
 		@PostConstruct
 		public void setupHooks() {
-			Hooks.onNewSubscriber((pub, sub) ->
-					new SpanSubscriber(sub, sub.currentContext(), this.tracer, pub.toString()));
+			Hooks.onNewSubscriber((pub, sub) -> {
+				//do not trace fused flows or simple just/error/empty
+				if(pub instanceof Fuseable && sub instanceof Fuseable.QueueSubscription
+						|| pub instanceof Fuseable.ScalarCallable){
+					return sub;
+				}
+				return new SpanSubscriber(sub, sub.currentContext(), this.tracer, pub
+						.toString());
+			});
 			Schedulers.setFactory(new Schedulers.Factory() {
 				@Override public ScheduledExecutorService decorateScheduledExecutorService(
 						String schedulerType,
diff --git a/spring-cloud-sleuth-reactor/src/test/java/org/springframework/cloud/sleuth/instrument/reactor/SpanSubscriberTests.java b/spring-cloud-sleuth-reactor/src/test/java/org/springframework/cloud/sleuth/instrument/reactor/SpanSubscriberTests.java
index 526957dc6..f3e2146d3 100644
--- a/spring-cloud-sleuth-reactor/src/test/java/org/springframework/cloud/sleuth/instrument/reactor/SpanSubscriberTests.java
+++ b/spring-cloud-sleuth-reactor/src/test/java/org/springframework/cloud/sleuth/instrument/reactor/SpanSubscriberTests.java
@@ -20,7 +20,12 @@ import org.springframework.cloud.sleuth.util.ExceptionUtils;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.test.context.junit4.SpringRunner;
+
+import org.reactivestreams.Subscriber;
+import org.reactivestreams.Subscription;
+import reactor.core.publisher.BaseSubscriber;
 import reactor.core.publisher.Flux;
+import reactor.core.publisher.Mono;
 import reactor.core.scheduler.Schedulers;
 
 import static org.assertj.core.api.BDDAssertions.then;
@@ -60,6 +65,70 @@ public class SpanSubscriberTests {
 		then(ExceptionUtils.getLastException()).isNull();
 	}
 
+	@Test public void should_support_reactor_fusion_optimization() {
+		Span span = this.tracer.createSpan("foo");
+		final AtomicReference<Span> spanInOperation = new AtomicReference<>();
+		log.info("Hello");
+
+		Mono.just(1)
+		    .flatMap( d -> Flux.just(d + 1).collectList().map(p -> p.get(0)))
+		    .map( d -> d + 1)
+		    .map( (d) -> {
+					spanInOperation.set(SpanSubscriberTests.this.tracer.getCurrentSpan());
+					return d + 1;
+				})
+		    .map( d -> d + 1)
+		    .subscribe(System.out::println);
+
+		then(this.tracer.getCurrentSpan()).isNull();
+		then(spanInOperation.get().getParents().get(0)).isEqualTo(span.getSpanId());
+		then(ExceptionUtils.getLastException()).isNull();
+	}
+
+	@Test public void should_not_trace_scalar_flows() {
+		Span span = this.tracer.createSpan("foo");
+		final AtomicReference<Subscription> spanInOperation = new AtomicReference<>();
+		log.info("Hello");
+
+		Mono.just(1)
+		    .subscribe(new BaseSubscriber<Integer>() {
+			    @Override
+			    protected void hookOnSubscribe(Subscription subscription) {
+				    spanInOperation.set(subscription);
+			    }
+		    });
+
+		then(this.tracer.getCurrentSpan()).isNotNull();
+		then(spanInOperation.get()).isNotInstanceOf(SpanSubscriber.class);
+
+		Mono.<Integer>error(new Exception())
+		    .subscribe(new BaseSubscriber<Integer>() {
+			    @Override
+			    protected void hookOnSubscribe(Subscription subscription) {
+				    spanInOperation.set(subscription);
+			    }
+
+			    @Override
+			    protected void hookOnError(Throwable throwable) {
+			    }
+		    });
+
+		then(this.tracer.getCurrentSpan()).isNotNull();
+		then(spanInOperation.get()).isNotInstanceOf(SpanSubscriber.class);
+
+		Mono.<Integer>empty()
+		    .subscribe(new BaseSubscriber<Integer>() {
+			    @Override
+			    protected void hookOnSubscribe(Subscription subscription) {
+				    spanInOperation.set(subscription);
+			    }
+		    });
+
+		then(this.tracer.getCurrentSpan()).isNotNull();
+		then(spanInOperation.get()).isNotInstanceOf(SpanSubscriber.class);
+		then(ExceptionUtils.getLastException()).isNull();
+	}
+
 	@Test
 	public void should_pass_tracing_info_when_using_reactor_async() {