Healthcare networks have been created to meet new health requirements. This new mode of organization gives healthcare professionals with different competences overall patient coverage. The aim of this study was to define tools supporting cooperation between these professionals. An ethnographic study on a healthcare network carried out during a period of one year has helped to understand how these networks function and what their requirements are. In this paper, we present the network studied, and describe a theoretical framework which can be used to analyze its activities; we focus in particular on the transactions taking place during face-to-face meetings, and we conclude that in order to cooperate efficiently, professionals need a coordination tool which is more than just an electronic patient file. We end this paper by suggesting guidelines for computer-supported cooperative activities in the field of healthcare networks.