diff --git a/lib/Transport.js b/lib/Transport.js
index 3ea692b3a..265f006f6 100644
--- a/lib/Transport.js
+++ b/lib/Transport.js
@@ -20,6 +20,7 @@
 'use strict'
 
 const debug = require('debug')('elasticsearch')
+const os = require('os')
 const once = require('once')
 const { createGzip } = require('zlib')
 const intoStream = require('into-stream')
@@ -34,6 +35,9 @@ const {
 
 const noop = () => {}
 
+const clientVersion = require('../package.json').version
+const userAgent = `elasticsearch-js/${clientVersion} (${os.platform()} ${os.release()}-${os.arch()}; Node.js ${process.version})`
+
 class Transport {
   constructor (opts = {}) {
     if (typeof opts.compression === 'string' && opts.compression !== 'gzip') {
@@ -46,7 +50,7 @@ class Transport {
     this.requestTimeout = toMs(opts.requestTimeout)
     this.suggestCompression = opts.suggestCompression === true
     this.compression = opts.compression || false
-    this.headers = opts.headers || {}
+    this.headers = Object.assign({}, { 'User-Agent': userAgent }, opts.headers)
     this.sniffInterval = opts.sniffInterval
     this.sniffOnConnectionFault = opts.sniffOnConnectionFault
     this.sniffEndpoint = opts.sniffEndpoint
diff --git a/test/unit/transport.test.js b/test/unit/transport.test.js
index b9e079dc3..867483863 100644
--- a/test/unit/transport.test.js
+++ b/test/unit/transport.test.js
@@ -22,6 +22,7 @@
 const { test } = require('tap')
 const { URL } = require('url')
 const { createGunzip } = require('zlib')
+const os = require('os')
 const intoStream = require('into-stream')
 const {
   buildServer,
@@ -2111,6 +2112,43 @@ test('Should accept custom querystring in the optons object', t => {
   t.end()
 })
 
+test('Should add an User-Agent header', t => {
+  t.plan(2)
+  const clientVersion = require('../../package.json').version
+  const userAgent = `elasticsearch-js/${clientVersion} (${os.platform()} ${os.release()}-${os.arch()}; Node.js ${process.version})`
+
+  function handler (req, res) {
+    t.match(req.headers, {
+      'user-agent': userAgent
+    })
+    res.setHeader('Content-Type', 'application/json;utf=8')
+    res.end(JSON.stringify({ hello: 'world' }))
+  }
+
+  buildServer(handler, ({ port }, server) => {
+    const pool = new ConnectionPool({ Connection })
+    pool.addConnection(`http://localhost:${port}`)
+
+    const transport = new Transport({
+      emit: () => {},
+      connectionPool: pool,
+      serializer: new Serializer(),
+      maxRetries: 3,
+      requestTimeout: 30000,
+      sniffInterval: false,
+      sniffOnStart: false
+    })
+
+    transport.request({
+      method: 'GET',
+      path: '/hello'
+    }, (err, { body }) => {
+      t.error(err)
+      server.stop()
+    })
+  })
+})
+
 test('Should pass request params and options to generateRequestId', t => {
   t.plan(3)