In the last decade, Activity Theory has been discussed a lot in Human-Computer Interaction (HCI) and Computer Supported Cooperative Work (CSCW). Activity Theory was used both theoretically as an analytical method and practically as a development framework for Information Systems. Meanwhile, there is a new trench from Artificial Intelligence. Artificial Intelligence researchers find that the fruit from Activity Theory study may contribute, especially to Agent Technology, with socio-psychological aspects. In our E-health research, we apply Activity Theory both theoretically and practically into Agent Technology. To facilitate our research, General Systems Theory is chosen to integrate Activity Theory and Agent Technology. On the one hand, we consider Activity Theory as specific subject of General Systems Theory. On the other hand, General Systems Theory contributes to Agent Technology with systematic perspectives. As integration, we introduce Activity Systems Theory as an extension of Activity Theory. Then we apply it into Agent Technology discussion. The paper starts with the discussion of systematic perspectives of Activity Theory. Then we introduce Activity Systems Theory as an integration of systems science and Activity Theory. Three Activity Systems Theory principles are then applied into the discussion of Agent Technology. In the end, we introduce how we apply Activity Systems Theory into an E-health application.