Utility of surgical margins in the radiotherapeutic management of soft tissue sarcomas. Seventy-four adult patients with localized soft tissue sarcomas were treated with radiation therapy following surgery between 1965 and 1988. Fifty-three were treated after the first excision of their tumor with 6 (11.3%) local recurrences. Twenty-one received radiation after excision of recurrent disease with 11 (52.4%) local failures (P less than .0005). Metastatic disease occurred in 14 (26.4%) of the primary tumors and 8 (38.1%) with multiple previous excisions (P less than .48). Of those patients treated for primary sarcoma, there were no local failures with pathologically wide margins or if a single margin was microscopically positive. Local failure occurred in 4 of 26 (15.4%) if the tumor was merely enucleated and in 2 of 11 (18.2%) who had grossly positive surgical margins (P not significant). Local failure was also more common in truncal locations (33.3%) as compared with extremity locations (8.7%, P = .1359). Additional factors analyzed which adversely affected prognosis included tumor grade, stage, and inadequate radiation dose. 