A retrospective evaluation was done of 15 patients (17 hips) with symptomatic osteonecrosis of the hip treated with core decompression combined with an allogeneic, antigen-extracted, autolyzed fibula allograft and 50 mg of partially purified human bone morphogenetic protein and noncollagenous proteins. The average duration of clinical followup of the patients was 53 months (range, 26-94 months). The osteonecrotic involvement of the hip was classified by plain radiographs using a modification of the Ficat staging system and MRI evaluations. Fifteen hips were classified as Ficat Stage IIA, one hip (one patient) was classified as Ficat Stage IIB, and one hip (one patient) was classified as Ficat Stage III. Fourteen hips had involvement of 50% or less of the femoral head and 2/3 or less involvement of the weight-bearing surface of the femoral head, based on a magnetic resonance imaging evaluation. The procedures were a clinical success in 14 of 15 hips (93%; 13 patients) with Stage IIA disease. Three of 17 hips (three patients) had radiographic progression (Ficat Stages IIA, IIB, and III) of the femoral head and were converted to total hip replacements. Only one of seven hips (six patients) with 50% or less involvement of the femoral head and between 1/3 and 2/3 of the weightbearing surface of the femoral head developed radiographic progression of the femoral head. There was no radiographic progression in the 3 hips with less than 1/3 involvement of the weightbearing surface of the femoral head. Further evaluation of the potential efficacy of bone morphogenetic protein is required in randomized trials.