We reviewed the long-term outcomes of treatment of fibrous dysplasia of the proximal part of the femur in twenty-two patients (twenty-seven femora). There were fifteen male patients and seven female patients. Patients who had monostotic disease had no involvement of the calcar femorale, fewer microfractures, less deformity, and stronger bone that could support internal fixation. Patients who had polyostotic disease had frequent involvement of the calcar femorale; more microfractures; severe deformity, including shepherd's crook deformity; and, in many instances, bone that could not support internal fixation. Twenty-two of the twenty-seven femora had a microfracture at the time of the initial presentation.At least one osteotomy was performed in four femora that had monostotic disease and in nine femora that had polyostotic disease. Curettage and cancellous or cortical bone-grafting did not appear to have any advantage compared with osteotomy alone in the treatment of symptomatic lesions, as all grafts resorbed with persistence of the lesion. At the time of the latest follow-up evaluation, no lesion had been eradicated or had decreased in size.A satisfactory clinical result was achieved in twenty patients (twenty-four femora): nine who had monostotic disease and eleven who had polyostotic disease. Two patients who had polyostotic disease and an endocrinopathy (one of whom had bilateral involvement) had an unsatisfactory result. All three femora in these two patients had a neck-shaft angle of less than 90 degrees at the time of the most recent follow-up evaluation.Varus deformity of the proximal part of the femur is best treated with valgus osteotomy and internal fixation early in the course of the disease. If the calcar of the femoral neck is involved or if the quality of the bone is such that internal fixation is not possible, a medial displacement valgus osteotomy can provide a more mechanically favorable position for healing of the microfracture.