PURPOSE: We wanted to evaluate the outcomes of an autologous osteochondral graft (Mosaicplasty) for treating chondral defects of the femoral condyle and We assessed the factors affecting the clinical results. MATERIALS AND METHODS: This study enrolled 18 patients (19 cases) who underwent an autogenous osteochondral graft to treat a osteochondral defect in the femoral condyle from July 2000 to June 2006. The average age was 26.2 years old (age range: 16-48 years old). Among the patients, 17 cases were men. In 14 cases, the osteochondral defects were localized in the medial femoral condyle and only 5 cases showed a defect in the lateral femoral condyle. The average size of the osteochondral defects was 4.2 cm2 (1-13 cm2). The Lysholm knee scoring scale and the Tegner's activity score were applied for clinical evaluation. Further, we carried out simple X-ray for all the cases and we performed MRI in 5 cases for the radiological evaluation. Tthe factors affecting the clinical results were also analyzed and the complications were evaluated. RESULTS: The average follow-up period was 22 months (range: 6-55 months). Eighten out of 19 cases (94.7%) were able to return to ordinary life. The Lysholm knee scoring scale and the Tegner's activity score indicated much better clinical results for small lesions and for young patients. For the radiological results, all the cases displayed a decrease in the size of radiolucent zones on the follow up X-ray. Among the 5 cases for which an MRI was performed, graft unions were observed in 3 cases, but 2 cases displayed continuous peri-graft edema. Any other complications involving the donor and recipient site were not observed. CONCLUSION: We conclude that autogenous osteochondral grafting is useful for specific patients depending on the size of the lesion and the patient's age. It is a valuable treatment option for osteochondral defects in the knee joint.