diff --git a/api/src/main/java/io/opentelemetry/metrics/DoubleCounter.java b/api/src/main/java/io/opentelemetry/metrics/DoubleCounter.java
index f84ee8ec9d3..5a031a82098 100644
--- a/api/src/main/java/io/opentelemetry/metrics/DoubleCounter.java
+++ b/api/src/main/java/io/opentelemetry/metrics/DoubleCounter.java
@@ -75,6 +75,7 @@ public interface DoubleCounter extends Counter<BoundDoubleCounter> {
    *
    * @since 0.1.0
    */
+  @ThreadSafe
   interface BoundDoubleCounter {
     /**
      * Adds the given {@code delta} to the current value. The values can be negative iff monotonic
diff --git a/api/src/main/java/io/opentelemetry/metrics/DoubleGauge.java b/api/src/main/java/io/opentelemetry/metrics/DoubleGauge.java
index 100b9c2f01d..2c04dcc5ad0 100644
--- a/api/src/main/java/io/opentelemetry/metrics/DoubleGauge.java
+++ b/api/src/main/java/io/opentelemetry/metrics/DoubleGauge.java
@@ -75,6 +75,7 @@ public interface DoubleGauge extends Gauge<BoundDoubleGauge> {
    *
    * @since 0.1.0
    */
+  @ThreadSafe
   interface BoundDoubleGauge {
 
     /**
diff --git a/api/src/main/java/io/opentelemetry/metrics/LongCounter.java b/api/src/main/java/io/opentelemetry/metrics/LongCounter.java
index f482686a6ec..f7a596a4a4c 100644
--- a/api/src/main/java/io/opentelemetry/metrics/LongCounter.java
+++ b/api/src/main/java/io/opentelemetry/metrics/LongCounter.java
@@ -75,6 +75,7 @@ public interface LongCounter extends Counter<BoundLongCounter> {
    *
    * @since 0.1.0
    */
+  @ThreadSafe
   interface BoundLongCounter {
 
     /**
diff --git a/api/src/main/java/io/opentelemetry/metrics/LongGauge.java b/api/src/main/java/io/opentelemetry/metrics/LongGauge.java
index c1b939cf172..76b35840c46 100644
--- a/api/src/main/java/io/opentelemetry/metrics/LongGauge.java
+++ b/api/src/main/java/io/opentelemetry/metrics/LongGauge.java
@@ -75,6 +75,7 @@ public interface LongGauge extends Gauge<BoundLongGauge> {
    *
    * @since 0.1.0
    */
+  @ThreadSafe
   interface BoundLongGauge {
 
     /**