Patients have different information and communication needs: information in order "to know", "to choose", "to pursue", "to produce", "to coordinate themselves". These needs depend on their disease, their attitude towards health, the characteristics of medical systems, and the available means of information. In many situations the Internet is an efficient means of information and communication which can be seen as complementary to contact with health professionals in the real world. The author distinguishes four types of service for patients: access to the content of web sites, participation in communities, e-communication with doctors, and applications which manage health professionals' data. These services are characterized by their "desirable" nature as far as some or all patients are concerned, and by the complexity of their implementation, that is, their being "possible" from a social point of view. They thus concern a fairly large number of patients and develop at differing paces. Their influence on different categories of information (knowledge, choices, supervision, production, coordination) varies.