The extensible Markup Language (XML) has been attracted much attention for expressing much of the Web?s content and data exchange. However, the use of the internet and multimedia technology these days has encouraged the intruders to copy the contents and illegal use of the data which is available on the internet or any other resources. Therefore the integrity protection of XML documents is becoming highly important. In this paper, we present a brief overview of XML related technologies and data security. Moreover, we introduce an experimental example for encrypting XML data based on chaos method.