The oncologic and functional outcome was reviewed in 21 consecutive patients who underwent limb salvaging surgery for periacetabular sarcoma using a new surgical approach and different types of reconstruction between 1972 and 1990. Histologic diagnosis in 86% showed osteosarcomas, chondrosarcomas, and Ewing's tumors. Age ranged from 10.0 to 61.5 years (mean age, 32.9 years). The resection margin was wide in 15 patients but marginal in 2 patients and intralesional in 4 patients. All of the latter patients died of their disease. In all cases where 3-dimensional imaging was used, wide resection margins could be achieved, whereas this was possible only in 50% of the cases with conventional imaging techniques. Seven patients died of their disease 3 to 15 months after surgery, 2 died of chemotherapy induced sepsis, and 2 patients died perioperatively. At followup, 8 patients had no evidence of disease (mean, 57.6 months; range, 12-190 months), and 2 patients were alive with disease. Fourteen patients could be observed for at least 12 months (mean, 41.1 months) and were functionally evaluated according to Enneking's criteria. If extensive resection was necessary, the best results were found if the defect had been reconstructed with a custom made prosthesis. The results were only satisfactory after implantation of saddle prostheses and poor with allografts or when no reconstruction of the bone defect was done.