In a period of one year blood samples of 374 sheep of Lower Austrian flocks were examined in intervals of two months for antibodies against Maedi-Visna (MV). Further on specific attention was paid to the prevalence of MV-infection in the flocks. The antibody-titers were determined by means of agar gel-immunodiffusion test. In 5 (23.8%) of 21 flocks 45 (12.0%) of the sheep were seropositive. Seroprevalence varied within the examined breeds: 19 (27.1%) of 70 Karakul-sheep, 18 (28.1%) of 64 East-Friesian milk-sheep, 7 (9.4%) of 74 Merino sheep and 1 (0.9%) of 111 mountain sheep. None of 55 black-headed sheep showed MV seropositive reaction. Clinical symptoms of Maedi-disease were especially observed in milk-sheep and for the first time in Austria in Karakul-sheep. Unfavorable housing conditions (insufficient room, bad climatic conditions), breed specific behavior patterns (crowding of Karakul-sheep) and a high prevalence of MV infections promote a high incidence the disease.