Medical care and research are highly specialised and distributed. Computer supported collaboration using local and wide area networks can essentially help to bridge the communication gaps between the various actors in health care and medical research. Hereby the full integration of medical image data plays a key role due to the fact that most decisions are made looking at images, e.g. an X-ray, an MRI, a photographic picture, an ECG curve and so on. In this paper three running pilot projects are presented which implement and evaluate different kinds of computer supported collaboration at a university hospital with emphasis on medical images: (I> A medical informatics research and development collaboration in endoscopy between image analysis experts and clinicians at different institutions. (2) A patient treatment collaboration between the physician at the nuclear reactor performing the radiation and the radiation planning experts at the Clinic of Radiation Therapy. (3) A medical research collaboration for acquisition of a second expert opinion during a clinical study in order to improve the quality of the study. The acceptance of these applications by the doctors in their research and clinical work is quite good. Their improvement requirements are objectives to already defined further projects.