diff --git a/hadoop-yarn-project/CHANGES.txt b/hadoop-yarn-project/CHANGES.txt
index d998803695..872edaf676 100644
--- a/hadoop-yarn-project/CHANGES.txt
+++ b/hadoop-yarn-project/CHANGES.txt
@@ -103,6 +103,9 @@ Release 2.0.5-beta - UNRELEASED
     YARN-450. Define value for * in the scheduling protocol (Zhijie Shen via
     bikas)
 
+    YARN-475. Remove a unused constant in the public API -
+    ApplicationConstants.AM_APP_ATTEMPT_ID_ENV. (Hitesh Shah via vinodkv)
+
   OPTIMIZATIONS
 
   BUG FIXES
diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-api/src/main/java/org/apache/hadoop/yarn/api/ApplicationConstants.java b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-api/src/main/java/org/apache/hadoop/yarn/api/ApplicationConstants.java
index 2fafffeb7e..bc016d8897 100644
--- a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-api/src/main/java/org/apache/hadoop/yarn/api/ApplicationConstants.java
+++ b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-api/src/main/java/org/apache/hadoop/yarn/api/ApplicationConstants.java
@@ -42,12 +42,6 @@ public interface ApplicationConstants {
    * only
    */
   public static final String AM_CONTAINER_ID_ENV = "AM_CONTAINER_ID";
-  
-  /**
-   * The environment variable for APPLICATION_ATTEMPT_ID. Set in AppMaster
-   * environment only
-   */
-  public static final String AM_APP_ATTEMPT_ID_ENV = "AM_APP_ATTEMPT_ID";
 
   /**
    * The environment variable for the NM_HOST. Set in the AppMaster environment
diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-applications/hadoop-yarn-applications-unmanaged-am-launcher/src/main/java/org/apache/hadoop/yarn/applications/unmanagedamlauncher/UnmanagedAMLauncher.java b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-applications/hadoop-yarn-applications-unmanaged-am-launcher/src/main/java/org/apache/hadoop/yarn/applications/unmanagedamlauncher/UnmanagedAMLauncher.java
index 62ac67fc17..605dc3b23d 100644
--- a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-applications/hadoop-yarn-applications-unmanaged-am-launcher/src/main/java/org/apache/hadoop/yarn/applications/unmanagedamlauncher/UnmanagedAMLauncher.java
+++ b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-applications/hadoop-yarn-applications-unmanaged-am-launcher/src/main/java/org/apache/hadoop/yarn/applications/unmanagedamlauncher/UnmanagedAMLauncher.java
@@ -57,10 +57,11 @@
  * unmanagedAM is an AM that is not launched and managed by the RM. The client
  * creates a new application on the RM and negotiates a new attempt id. Then it
  * waits for the RM app state to reach be YarnApplicationState.ACCEPTED after
- * which it spawns the AM in another process and passes it the attempt id via
- * env variable ApplicationConstants.AM_APP_ATTEMPT_ID_ENV. The AM can be in any
- * language. The AM can register with the RM using the attempt id and proceed as
- * normal. The client redirects app stdout and stderr to its own stdout and
+ * which it spawns the AM in another process and passes it the container id via
+ * env variable ApplicationConstants.AM_CONTAINER_ID_ENV. The AM can be in any
+ * language. The AM can register with the RM using the attempt id obtained
+ * from the container id and proceed as normal.
+ * The client redirects app stdout and stderr to its own stdout and
  * stderr and waits for the AM process to exit. Then it waits for the RM to
  * report app completion.
  */