Telemedical information systems (TIS's) form the basis for telemedicine services as well as for health information services. This paper gives an introduction to the wide scope of TIS's and discusses examples for the different types of TIS's: patient-related TIS's, knowledge-related TIS's, and meta-TIS's. It concludes that for patient-related TIS's there is the need for a better integration of TIS's with other patient-centered information systems. For the other types of TIS's, more sophisticated retrieval techniques and better user interfaces for ordinary users are required. Furthermore, short descriptions of our own projects are given: the patient-related TIS of the project TECSAC (distributed electronic patient record for cardiology) and the domain-specific knowledge-related TIS's ODITEB (radiological Internet text-book) and ENDOTEL-EIS (endoscopy information system).