In this paper we present an Agent-based Open Service Architecture (OSA) which integrates geographically distributed agents in the Web. Agents can be realized with traditional AI techniques, but they also provide a set of Web Services to the outside world which constitute their capabilities. The architecture extends the Web with a facilitator level providing agents’ specific support. Moreover it provides primitives for Web Services invocation and inter-agent communication based on Agent Communication Languages. We present the design of the architecture and an implementation which extends a common Web Server based on Apache/Tomcat platform.