MEDICUS is a teleradiology system which has been developed in a joint project of the German Cancer Research Center (Deutsches Krebsforschungszentrum) and the Transfer Center Medical Informatics (Steinbeis-Transferzentrum Medizinische Informatik) in Heidelberg, Germany. The system is designed to work on ISDN lines as well as in a local area network. Special attention has been given to the design of the user interface and data security, integrity, and authentication. The software is in use in 13 radiology departments in university clinics, small hospitals, private practices, and research institutes. More than 25 thousand images have been processed in 6 months. The system is in use in six different application scenarios. MEDICUS is running under the UNIX operating system. The connection of the modalities could in most cases not be realized with the DICOM protocol as older machines were not equipped with this standard protocol. Clinical experiences show that the MEDICUS system provides a very high degree of functionality. The system has an efficient and user friendly graphical user interface. The result of a comparison with other systems shows that MEDICUS is currently the best known teleradiology system. Cost reductions are already obvious, but additional research has to be performed in this field. An even more powerful commercial successor is currently under construction at the Steinbeis-Transferzentrum Medizinische Informatik in Heidelberg.