Seventeen consecutive patients were managed with an allograft reconstruction of the pelvis (including the acetabulum) following resection of a stage-IIB bone sarcoma during a twelve-year period. The initial diagnosis was chondrosarcoma in nine patients, osteosarcoma in six, Ewing sarcoma in one, and leiomyosarcoma in one. All patients who had osteosarcoma or Ewing sarcoma received chemotherapy preoperatively and postoperatively. Fifteen patients were managed with an allograft-total hip prosthesis composite. Two patients initially were managed with an osteoarticular allograft without a prosthesis, but one had a subsequent revision to an allograft-implant composite. Four patients died with an intact allograft reconstruction. Eight patients survived with an intact allograft reconstruction, and they were followed for at least four years (mean, seven years; maximum, fourteen years). All but one was able to walk in the community with one or two canes at the time of the latest follow-up. There was a high rate of local recurrence, which occurred in three of the seventeen patients, and of infection, which developed in two patients. The five patients had a subsequent hindquarter amputation or removal of the allograft. The mean functional score (and standard deviation), according to the rating system of the Musculoskeletal Tumor Society, was 65 +/- 21.16 per cent (median, 70 per cent; range, 13 to 87 per cent) for the thirteen patients who were thus evaluated. Preservation of the limb and reconstruction with an allograft may be considered as an alternative to hindquarter amputation in carefully selected patients who have a bone sarcoma involving the acetabulum. However, patients who have a high-grade bone sarcoma must be warned that there is a substantial risk of local recurrence or infection. In the present series, more than half of the patients either died or had failure of the reconstruction.