The functional outcome of acetabular reconstruction in 21 patients with severe acetabular deficiency was examined. The surgical indications were pain, immobility, and loss of indepedence. Surgical reconstruction included curettage, placement of an acetabular roof ring with screws crossing the defect, cementation of the defect, and cemented hip arthroplasty. Although three patients died within the first month, the mean postoperative survival was 14.5 +/- 4.0 months, with a 10.4 +/- 3.0-month period of independent living. Statistically significant postoperative improvements were seen in pain and mobility scores. Using the Musculoskeletal Tumor Society score for the lower extremity, a mean postoperative score of 14.2 of a total 30 was calculated. Low scores were attributed to the patients' overall disease, including the requirement of continued narcotic pain control, occupational restriction, and the presence of Trendelenburg limp. Surgical complications occurred in six patients and included three early postoperative deaths, two related to poor preoperative pulmonary function; two dislocations, one related to a late infection; one femoral nerve palsy; and one foot drop. Although associated with a high complication rate, acetabular reconstruction for metastatic disease can lead to marked improvement in pain control, function, independence, and quality of life in carefully selected patients.