Between 1968 and 1982, 10 children (7 boys and 3 girls) with a mean age of 3.2 years affected by bladder (8 cases) and prostate (2 cases) rhabdomyosarcoma (RMS)--all histologically embryonal--were seen. Three (1 with bone metastases at diagnosis and 2 with stage III tumor) underwent radical surgery; all died because of progression of the disease. Seven children were treated with conservative surgery: 3 solid type bladder tumors were removed together with a narrow strip of apparently healthy bladder wall, sparing 30% to 70% of the bladder; 3 botryoid type bladder tumors were removed bluntly and implantation sites fulgurated; in 1 prostate tumor osmotic cytolysis of the neoplastic mass was achieved with multiple injections of hypertonic saline solution (NaCl 30%). Surgery was followed by chemotherapy with a vincristine actinomycin D and cyclophosphamide protocol and radiotherapy (20 to 39.5 Gy). Six of the seven are alive and disease free with a normal functional bladder after 10 to 21 years. The validity of a primary conservative surgical approach with preservation of the bladder, followed by adjuvant therapy, is emphasized.