diff --git a/lib/ldclient-rb/events.rb b/lib/ldclient-rb/events.rb
index 184facc4..bb12f6ec 100644
--- a/lib/ldclient-rb/events.rb
+++ b/lib/ldclient-rb/events.rb
@@ -1,6 +1,7 @@
 require "concurrent"
 require "concurrent/atomics"
 require "concurrent/executors"
+require "securerandom"
 require "thread"
 require "time"
 
@@ -359,6 +360,7 @@ def run(sdk_key, config, client, payload, formatter)
       events_out = formatter.make_output_events(payload.events, payload.summary)
       res = nil
       body = events_out.to_json
+      payload_id = SecureRandom.uuid
       (0..1).each do |attempt|
         if attempt > 0
           config.logger.warn { "[LDClient] Will retry posting events after 1 second" }
@@ -374,6 +376,7 @@ def run(sdk_key, config, client, payload, formatter)
           req["Authorization"] = sdk_key
           req["User-Agent"] = "RubyClient/" + LaunchDarkly::VERSION
           req["X-LaunchDarkly-Event-Schema"] = CURRENT_SCHEMA_VERSION.to_s
+          req["X-LaunchDarkly-Payload-ID"] = payload_id
           req["Connection"] = "keep-alive"
           res = client.request(req)
         rescue StandardError => exn
diff --git a/spec/events_spec.rb b/spec/events_spec.rb
index 16bee286..1108a3ac 100644
--- a/spec/events_spec.rb
+++ b/spec/events_spec.rb
@@ -416,6 +416,29 @@
     expect(hc.get_request["authorization"]).to eq "sdk_key"
   end
 
+  it "sends unique payload IDs" do
+    @ep = subject.new("sdk_key", default_config, hc)
+    e = { kind: "identify", user: user }
+  
+    @ep.add_event(e)
+    @ep.flush
+    @ep.wait_until_inactive
+    req0 = hc.get_request
+
+    @ep.add_event(e)
+    @ep.flush
+    @ep.wait_until_inactive
+    req1 = hc.get_request
+
+    id0 = req0["x-launchdarkly-payload-id"]
+    id1 = req1["x-launchdarkly-payload-id"]
+    expect(id0).not_to be_nil
+    expect(id0).not_to eq ""
+    expect(id1).not_to be nil
+    expect(id1).not_to eq ""
+    expect(id1).not_to eq id0
+  end
+
   def verify_unrecoverable_http_error(status)
     @ep = subject.new("sdk_key", default_config, hc)
     e = { kind: "identify", user: user }
@@ -442,8 +465,15 @@ def verify_recoverable_http_error(status)
     @ep.flush
     @ep.wait_until_inactive
 
-    expect(hc.get_request).not_to be_nil
-    expect(hc.get_request).not_to be_nil
+    req0 = hc.get_request
+    expect(req0).not_to be_nil
+    req1 = hc.get_request
+    expect(req1).not_to be_nil
+    id0 = req0["x-launchdarkly-payload-id"]
+    expect(id0).not_to be_nil
+    expect(id0).not_to eq ""
+    expect(req1["x-launchdarkly-payload-id"]).to eq id0
+    
     expect(hc.get_request).to be_nil  # no 3rd request
 
     # now verify that a subsequent flush still generates a request