diff --git a/README.md b/README.md
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@@ -107,6 +107,7 @@ View Chinese translation: [恶意软件分析大合集.md](恶意软件分析大
   of malware sample sources put together by Lenny Zeltser.
 * [Zeus Source Code](https://github.com/Visgean/Zeus) - Source for the Zeus
   trojan leaked in 2011.
+* [VX Underground](http://vx-underground.org/) - Massive and growing collection of free malware samples.
 
 ## Open Source Threat Intelligence