Thirty-five patients who had had a primary total hip replacement with a porous-coated acetabular component inserted without cement had a revision procedure to treat pelvic osteolysis. The mean age at the time of the revision operation was forty-nine years (range, twenty-nine to eighty-five years). Forty-six distinct pelvic osteolytic lesions were noted radiographically around the thirty-five cups. These lesions ranged in size from 0.5 by 0.5 centimeter to 6.3 by 2.7 centimeters (mean, 2.6 by 1.7 centimeters). Fourteen of the thirty-five patients had no or only slight occasional pain at the time of diagnosis of the pelvic osteolysis, fifteen patients had pain attributed to a loose femoral component, one had pain related to a spontaneous fracture of the greater trochanter, and one had pain related to recurrent subluxation. The remaining four patients had pain in the groin despite radiographically stable implants. All of the metal-backed porous-coated acetabular components were stable according to the preoperative radiographs, and the stability was confirmed at the time of the revision. The metal shell was left in place and the acetabular liner was exchanged in all thirty-five patients. The osteolytic lesions were debrided, and thirty-four of the forty-six lesions were filled with allograft bone chips. The patients were evaluated a minimum of two years (range, two to five years; mean, 3.3 years) after the revision operation, and all thirty-five sockets were found to be radiographically stable. The bone grafts appeared to have consolidated, and none of the osteolytic defects had progressed. One-third of the lesions were no longer visible on radiographs, regardless of whether or not they had been filled with bone graft. The remaining lesions had decreased in size. It appears that, in the short-term, exchange of the liner and debridement of the granuloma, with or without use of allograft bone chips in the osteolytic defect, is a reasonable alternative to revision of the socket provided that the metal shell is solidly fixed at the time of the revision operation. If the metal shell has been markedly damaged by the femoral head, the locking mechanism for the polyethylene liner is not intact, or a satisfactory replacement liner is not available, then revision of the porous-coated acetabular component is indicated. These results must be considered preliminary. Since osteolysis may take several years to redevelop after a revision, additional follow-up is required.