BACKGROUND: Health care professionals' collaboration is highly important for the medical practice. Efficient exchange of information improves good cooperation, but remains complex, due to the diversity of the medical activities. Currently, the health record is mainly used to manage structured medical information. On the one hand, such structure supports treatment that requires the documented information. On the other hand, however, the structure also imposes constraints on narrative and conversational practices of health care professionals. They use other collaboration means through phone, mail, annotations and free texts for informal strategies of communication. We focussed on informal written documents. Two different studies provided us some materials: home care charts in the context of home care and annotations in the context of the hospital health records. PURPOSES: We wanted to design a model of the Communication Notes to computerize the written notes so as to improve the communication and the coordination of the practitioners. METHODS: We compared the results of the two studies about the various writing strategies used by the health care professionals to keep traces of their exchanges and of their acts. The first study deals with the information mentioned by the nurses in a chart during home care situations. We analysed the distribution of cooperation activities in action and in planning. The second study deals with the annotations which are written by all the practitioners to complete the documents of the health record in a paediatric ward. We analysed how annotations take part in their collaborations. RESULTS: We found some invariable items in these two situations and we proposed a model for these Communication Notes which can be used to describe and to index them according to different points of view. Some indications on the way such descriptions are used in current computerized systems are also reported. The originality of this model comes from the way it takes into account a collaborative perspective which is not often used in the electronic medical settings. CONCLUSIONS: With our model of Communication Notes, we now dispose of a promising setting for managing all the informal and unforeseeable information produced by the health care professionals during care.