The best indication for corrective osteotomy of the head of the tibia is unilateral osteoarthrosis of the knee joint in which the apical angle of the deformity lies in the head of the tibia or in the joint. Full-length radiographs of the leg are indispensable to determine the level of the osteotomy and the angle of correction required. The indications for high openwedge osteotomy of the tibial condyles and high osteotomy of the head of the tibia are discussed, and some of the technical details of the osteotomy and its fixation are described. Between 1970 and 1977, 139 corrective osteotomies of the head of the tibia were carried out in our clinic. Seventy nine adult patients with 100 operated knees were followed up approximately 3.5 years after operation. In 80% there was an improvement with regard to pain and walking distance when compared with the praeoperative state. The results depend on the kind of deformity (varus deformities generally show a better result) and the seriousness and duration of pre-existing osteoarthrosis and laxity of the ligaments.