To analyze the medium and long term results of high tibial osteotomy(HTO) for the treatment of knee joint osteoarthritis(OA). From January 2001 to December 2005, 45 patients(63 knees)with medial compartment OA were treated with HTO, including 10 males (15 knees) and 35 females (48 knees), ranging in age from 45 to 64 years old with an average of (55.76±5.54) years old. Preoperative normal anteroposterior and lateral X ray films of weight bearing knee were conducted, with an accurate measurement of the femoral tibial angle(FTA), and the mass of lateral tibial osteotomy was determined according to the preoperative FTA. Routine HTO was performed after epidural anesthesia. Most patients were treated with middle part fibulae osteotomy, and some patients were treated with the release of proximal tibiofibular joints. The functional exercise no weight bearing ambulation and weight bearing exercise began on the second day after operation 2 weeks after operation and 8 to 10 weeks after operation respectively. All the cases should be examined with X ray postoperatively on the second day, 8 to 10 weeks, 6 months, 1 year after operation and once a year. The VAS, HSS and KSS were used to evaluate knee pain, deformity, function, and range of motion preoperatively, 3 to 5 years postoperatively, 10 to 14 years postoperatively in all the patients. Forty three patients (61 knees) were followed up for more than 10 years. All the incisions were healed at the first stage. The bone healing was achieved 8 to 10 weeks after operation. The knee joint was evaluated according to the HSS standard 10 to 14 years after operation, and the average score was 76.24±5.27. Twenty seven patients got an excellent result, 25 good, 7 fair and 2 poor. The VAS, HSS and KSS scores of postoperative 3 to 5 years and 10 to 14 years were better than those of before operation. There were no obvious differences of scores between postoperative 3 to 5 years and postoperative 10 to 14 years. The long term curative effect of high tibial osteotomy in the treatment of knee OA(medial compartment arthritis) is satisfied, if the indications for surgical treatment are appropriate, and postoperative active exercises are performed.