The World Wide Web is now the most used multimedia information system on Internet allowing, by means of Web browsers such as Netscape Navigator or Mosaic, distribution or consultation of hypermedia documents. Although the Web has appeared only recently, the growth of its use has generated the emergence of numerous information and knowledge bases in the medical field. We suggest to investigate extended functionalities in order to introduce cooperative activities in our medical information system. These new activities allow asynchronous exchange of records and synchronous cooperation for a better coordination of the work within and between hospitals.