Osteochondral allografts were used in 11 patients with osteochondritis dissecans and 4 with osteonecrosis of the femoral condyles. The lesions were mainly in the medial condyle in 13 cases, and in the weightbearing area in 10. The grafts had a mean size of 6 cm2; 8 were kept in hypothermia at 4 degrees C for less than 24 h and 7 were stored at -80 degrees C with cryoprotection. After an average follow up of 3.2 years, only 2 patients needed a further operation, one for nonunion and the other for a fracture of the graft. The others had improved clinically and showed radiological union of the graft with preservation of the joint space.