In a clinical study of 35 dogs with avascular necrosis of the femoral head, 60 per cent were Yorkshire terriers; the mean age of 33 of the dogs at onset of clinical signs was seven months. The dogs had the following signs: muscle atrophy (n = 25), shortening of the affected leg (n = 14), pain on passive movement of the hip joint (n = 28), and crepitation of the hip joint (n = 8). Radiographic findings were irregular density and flattening of the femoral head in combination with degenerative joint disease. Conservative treatment consisted of exercise therapy, and surgical treatment of a standard femoral head and neck excision. In 17 of the dogs the results of therapy were evaluated with the help of a questionnaire. It is concluded that femoral head and neck excision is indicated when conservative treatment fails to lead to clinical improvement within four weeks. Femoral head and neck excision has a good long term prognosis; however, slight intermittent lameness may remain.