In 1958, Jackson first reported on the use of proximal tibial osteotomy in the treatment of pain due to osteoarthritis of the knee joint. Subsequently, various osteotomy techniques have been reported. The varus deformity of the knee associated with osteoarthritis can be corrected by realigning the joint and thereby shifting the line of weight bearing to the compartment with preserved articular cartilage. This procedure has been found to relieve pain, improve function and arrest the progress of the condition. Twenty five cases of genu varum associated with osteoarthritis were treated by high tibial osteotomy at Dept. of O.S., Seoul National University Hospital, from July 1976 to June 1983. And the following results were obtained. 1. In a review of 25 high tibial osteotomies, excellent and good results were noted in 80% of the knees after average follow-up 2.9 years. 2. Postoperative valgus angles, ranging from 5° to 20°, were averaged to be 10.8°. 3. Though some authors indicate the obesity as one of risk factors, we obtained satisfactory results in 25 knees of obese patients.