From 1974 to 1983 we treated 16 children between 1 and 16 years old for soft tissue sarcoma arising in the pelvis, bladder or prostate. An incisional biopsy was obtained in every patient. Each child then was treated with a combination chemotherapy program, incorporating vincristine, actinomycin D and cyclophosphamide with or without doxorubicin, cis-platinum and etoposide. Of the 16 patients 13 (81 per cent) also received radiation therapy. In 8 children with urinary obstruction or hematuria sarcomas arose in the bladder or bladder-prostate region, including 7 who had localized tumors and 1 who had lung metastases at diagnosis. The median tumor diameter in these patients was 5 cm. Of these 8 patients 3 eventually required total cystectomy and prostatectomy to eradicate persistent local tumor, and 6 are alive and remain free of recurrent sarcoma for 1 to 9 years after initiation of therapy. The 8 other children had a pelvic mass at diagnosis, which arose adjacent to but outside of the bladder or prostate, and 2 had lung metastases at diagnosis. The median tumor diameter in these patients was 15 cm. Only 3 of these 8 children are alive and remain free of sarcoma for 1 to 8 years after initiation of therapy. In only 1 of these children was complete tumor excision ever possible despite the use of local radiation therapy and aggressive chemotherapy. Sarcomas arising in the bladder-prostate region are found when relatively small, perhaps because they soon produce overt signs, and they appear to have a better prognosis than those arising in the retroperitoneum-pelvis outside the bladder. Better treatment strategies are needed for the latter group of tumors that often are locally uncontrollable.