The results of twenty-three distal femoral varus osteotomies (in twenty-one patients) that were performed between 1977 and 1984 were evaluated. Fifteen osteotomies were done for osteoarthritis; three, for post-traumatic arthritis or deformity; three, for rheumatoid arthritis; and two, for renal osteodystrophy. The median age of the patients was fifty-six years (range, nineteen to seventy years). The length of follow-up averaged four years (range, two to nine years). The average tibiofemoral angle preoperatively was 18 degrees of valgus, which was corrected postoperatively to an average of 2 degrees of valgus. At follow-up, nineteen (83 per cent) of the twenty-three knees were rated as good or excellent according to The Hospital for Special Surgery knee score, which had improved from an average of 65 points preoperatively to 86 points post-operatively. Of the fifteen patients who had osteoarthritis (93 per cent), all but one had a good or excellent result. Most patients had no substantial improvement in the range of motion of the knee as a result of the operation. Eighty-six per cent of the patients expressed satisfaction with the outcome. We concluded that varus osteotomy of the distal part of the femur is a reliable and effective surgical procedure for the treatment of gonarthrosis associated with valgus deformity due to osteoarthritis or trauma. We do not recommend its use in patients who have rheumatoid arthritis or in those who have inadequate motion of the knee before the operation.