Within the scope of this thesis the development of the present knowledge about Canine Distemper throughout history is described. Different opinions of practitioners, scientists and amateurs during the single eras as well as the problems and errors while coping with one of the most dangerous diseases of dog are explained. One can trace early occurrence of Canine Distemper up to the age of Aristoteles. Since 1761 Canine Distemper spread through europe. At this time numerous presumptions exist regarding the etiology of the disease, and corresponding to this the methods of treatment were quite adventurous. In 1809 Jenner was probably one of the first who gave a more reliable description of Canine Distemper. Also the first attempts to develop a vaccination took place in this period. At the end of the 19th century Canine Distemper was described as the probably most frequent disease of dog. Up to this time various bacteriological findings failed to proove associations with Canine Distemper. The diagnosis was set up exclusively by clinical symptoms which were described well at this time. However, the prognosis ever was formulated. The situation about 1900 was characterized by an intensive search for the infectious agent of Canine Distemper, for possibilities of therapy and prophylaxis. In 1905 Carre succeded to reproduce the disease in susceptable dogs with germ-free nasal mucus of infected dogs. By this experiment the virus etiology was prooved basically and confirmed finally in 1926 by Duncin and Landlow who established the ferret as an adequate test animal in the Distemper research. In the middle of the 20th century the germ of Canine Distemper was recognized as a virus of the morbilli genus in the paramyxo virus family. In this period one succeeded also in adapting the virus to embryonated eggs and in cultivating it in culture tissues. These to milesteps met the requirements for developing a vaccine. Due to immunoprophylaxis and antibiotic treatment the classical clinical appearance of Canine Distemper changed. Modern methods of virology and molecular biology lead to new insights in the nature of this RNA virus. The disease transfer to man resp. ist contribution to other diseases was discussed, but could not be confirmed until now. All Canidae, Procyonidae and Mustelidae are considered to be susceptible. Despite vaccination Canine Distemper is next to Canine Parvovirosis still the most important viral disease of dog with worldwide importance attributable to ocasional epidemics. The dog is the main reservoir of the virus. There is a need for more investigations concerning the importance of wild species as virus reservoir. From the present status of knowledge a causal therapy of Cannine Distemper is impossible. Prophylaxis by vaccination is still the most important disease prevention. Conclusively, Canine Distemper still has to be considered as a disease with an uncertain prognosis.