web services technology is an emerging paradigm in establishing a standard environment for legacy applications integration over the internet. using web services and related technologies facilitate the implementation of a virtual enterprise across heterogeneous software platforms. however, web services suffer from some shortcomings fulfilling requirements of setting up a reactive and autonomous collaboration among enterprises. the current technology' of web services registry, known as uddi, is in its infancy stage. the aim of this work is to integrate intelligent software agents and web services in order to apply them to create a collaborative environment. we s ta rt with describing the concepts of virtual enterprise, web services, and software agents as well as their requirements, problems, and benefits. to this extent, we identify the existing problems w ith web services technology and discuss the feasibility of using software agents and their abilities to prevail those difficulties. this thesis proposes a web services / agent-based model for both the internal architecture of an individual enterprise and the uddi registry as well. we define a multi-agent model in different levels of enterprise’s system architecture to accomplish a suitable selection of a registered service, to check the status of a process, to realize users’ requests, and to react to them in a collaborative way with other agent-based web services. moreover, the thesis proposes a multi-agent model to define a dynamic workflow capable of coordinating and monitoring the processes defined in the workflows.