Osteosynthesis using K-wires was applied to 27 proximal femur fractures in a total of 26 animals with either femora! head or neck fractures, of which 18 were dogs (10 femoral head arid 9 femoral neck fractures) and 8 were cats (4 femoral neck and 4 femoral head fractures). Results of the operations were evaluated. Full recovery was observed in 20 fractures belonging to 19 cases. In 5 cases, however, fixation was unsuccessful and excision arthroplasty was carried out.