From July 1982 to December 1989, 43 of 1,583 adults (2.7%) with soft tissue sarcoma admitted to the Memorial Sloan-Kettering Cancer Center (MSKCC) had tumors arising from the urinary tract and male genital tract (urological sarcoma). The most common site of origin of the tumor was paratesticular (14 patients), followed by the prostate/seminal vesicle (12), bladder (10) and kidney (7). The most common histological type was leiomyosarcoma (19 patients), followed by rhabdomyosarcoma (14), liposarcoma (5) and 5 other histological sarcoma categories (angiosarcoma, malignant fibrous histiocytoma, mesenchymoma and 2 undifferentiated sarcomas). Most of the tumors were high grade (86%) and more than half (56%) were greater than 5 cm. in diameter. A total of 9 patients (21%) presented with metastatic disease, 8 of whom had rhabdomyosarcoma. Complete resection with negative microscopic margins was possible in 58% of the patients. Actuarial relapse-free survival for all patients at 3 and 5 years was 55% and 40%, respectively. There were no significant differences in survival based on patient age, sex or histological tumor type. Favorable prognostic variables by univariate analysis included tumor diameter less than 5 cm., low histological grade, paratesticular or bladder tumor site and complete surgical resection. Application of the MSKCC sarcoma staging system, which is based on grade, size, depth and presence or absence of metastasis, was useful to predict survival. In our experience patients with stage 3 (high grade, greater than 5 cm., 15 patients) or stage 4 (metastatic disease, 9 patients) had a combined 3-year relapse-free survival rate of only 26% and they should be considered candidates for adjuvant treatment protocols.