Thirty-two biplane osteotomies in thirty patients were performed for the treatment of chronic slipped capital femoral epiphysis during a fourteen-year period at the Jersey City Medical Center. Twenty-seven patients (twenty-nine hips) were followed for two and a half to fourteen years. The correction obtained at surgery was maintained in all of the patients. Although two patients had had narrowing of the hip joint preoperatively and one had narrowing postoperatively, this had resolved at an average of three years postoperatively. Improvement in the range of motion was noted. In twenty patients the limb lengths were equal, in three the involved limb was longer, and in four patients the limb was shorter postoperatively. One patient had a slight subluxation of the femoral head due to an excessive valgus correction at the time of surgery, and one patient had delayed union of the osteotomy site which went on to satisfactory healing. No patients had avascular necrosis of the femoral head or symptoms of degenerative arthritis at follow-up. Preoperative joint-space narrowing did not appear to be a contraindication to this procedure.