Records of 323 patients with TNM Stage M0 sarcoma of soft tissue treated by the Radiation Medicine Service of the Massachusetts General Hospital over a 14-year period were reviewed to study the incidence and the implication of regional lymph node involvement. Nineteen patients (5.9%) had evidence of sarcoma metastatic to draining lymph nodes, zero of 63 (0%) were Grade 1 sarcomas, two of 118 (2%) were Grade 2, and 17 of 142 (12%) were Grade 3 sarcomas. Among patients with Grade 3 sarcomas, rhabdomyosarcoma (five of 14), vascular sarcoma (two of five), and epithelioid sarcoma (four of five) were associated with a higher incidence of lymph node involvement than synovial sarcomas (zero of four), fibrosarcomas (zero of 16), malignant fibrohistiocytomas (one of 29), neurofibrosarcomas (one of eight), liposarcomas (one of 14), and leiomyosarcomas (one of ten). From the 19 patients who had evidence of metastatic nodes, six (32%) were alive more than 58 months after the treatment of the nodes; four of six patients were without further tumor. The data of this study are compared with those cited in a review of the literature.