diff --git a/README.md b/README.md
index 8d104bb..00e70c8 100644
--- a/README.md
+++ b/README.md
@@ -30,6 +30,7 @@ All requests require these two fields to be specified:
 All responses will include these fields:
 - `id` (string): corresponding to the request ID
 - `success` (boolean): whether or not the request was successful
+- `execution_time` (long): elapsed time in millis
 
 If an error occurs, all responses will include these fields:
 - `error`: a description of the error
diff --git a/src/main/java/com/github/ibm/mapepire/ClientRequest.java b/src/main/java/com/github/ibm/mapepire/ClientRequest.java
index e05abb9..31399cd 100644
--- a/src/main/java/com/github/ibm/mapepire/ClientRequest.java
+++ b/src/main/java/com/github/ibm/mapepire/ClientRequest.java
@@ -5,6 +5,7 @@
 import java.sql.SQLException;
 import java.util.LinkedHashMap;
 import java.util.Map;
+import java.util.concurrent.TimeUnit;
 
 import com.github.theprez.jcmdutils.StringUtils;
 import com.google.gson.Gson;
@@ -81,6 +82,7 @@ protected void processAfterReplySent() {
 
     @Override
     public void run() {
+        long startTime = System.nanoTime();
         try {
             go();
             addReplyData("success", true);
@@ -95,6 +97,7 @@ public void run() {
             }
         } finally {
             try {
+                addReplyData("execution_time", TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - startTime));
                 sendreply();
                 processAfterReplySent();
             } catch (final Exception e) {