After an introductory description of the subfamily lentivirinae and the relations between Maedi/Visna virus and caprine arthritis encephalitis (CAE) virus und HIV, the present knowledge on CAE, including the clinical picture, pathological lesions, global distribution and transmission studies, is outlined. Other interesting features are briefly presented together with an explanation of why CAE could be used as a simple, nonprimate model in HIV research, especially for the evaluation of the effect of treatment compounds developed, of the efficacy of vaccines and the study of the effect of immunostimulants.