Osteochondritis dissecans in two adults with a large osteochondral defect on the weight-bearing surface was treated by transplantation of an autogeneic osteochondral fragment. The graft was transplanted from the normal portion of the medial femoral condyle, which in extension was in contact with neither patella nor meniscus. The donor site was repaired with an iliac bone fragment. After curettage of the crater, the osteochondral fragment was transfixed with AO mini-cancellous screw(s). Six months after the operation, the grafted cartilage of one patient looked the same as normal cartilage when macroscopically observed and showed no sign of histologic degeneration. At the follow-up examination, the patients were asymptomatic. One patient had a full range of motion two years and three months later; the other three years later. Roentgenographic examinations revealed slight irregularities at the grafted site. There was no significant change in the patellofemoral joint except the concavity of the donor site.