High tibial osteotomy is a reliable method for relieving pain in the varus osteoarthritic knee. In a review of 139 osteotomies, excellent and good results were noted in 64% of the knees after a follow-up period of at least ten years. The ideal candidate for this operation has Grade I or II osteoarthritis; less than 10 degrees of varus deformity, as measured by a single leg standing roentgenogram; no lateral subluxation; and no instability. The lateral closed wedge osteotomy without internal fixation is the preferred technique, and correction beyond the normal anatomic position, to 5 degrees of valgus, is advised. Protected weight-bearing after the second postoperative day is allowed. Complications have been infrequent and minor. Forty-seven knees were managed in this manner, and 88% had an excellent or good result at a four-year follow-up evaluation. In the majority of the well corrected knees, the alignment did not change with time, and the osteoarthritis did not progress. No failures in this series were attributable to the associated patellofemoral osteoarthritis; the reaction of the patellofemoral joint to osteotomy is obscure.