We treated 31 soft tissue sarcoma bearing patients with intraoperative radiation therapy (IORT) with ages ranging from 26 to 71: first curative intent treatment, 16 patients; and recurrent tumors, 15 patients. The tumor site was the pelvis and the retroperitoneal spaces in 13 patients and the limbs or the trunk in 18 patients. The histological type was: malignant histiocytofibroma, 14 patients; liposarcomas, 10 patients; malignant schwanoma, 1 patient; leiomyosarcoma, 2 patients; hemangiopericytoma, 1 patient; embryonic rhabdomyosarcoma, 2 patients; and synovialosarcoma, 1 patient. All the patients were diagnosed without any distant metastatic evolution at the moment of the treatment. All the patients except one underwent a complete surgical excision without any gross residual disease and received an intraoperative radiation single dose of 10 Gy in one case, 12.5 Gy in one case, 13 Gy in one case, 15 Gy in 17 cases, 18 Gy in three cases, 20 Gy in seven cases and 25 Gy in one case. Thereafter the treatment was completed by a postoperative X-ray dose of 45-50 Gy in 4.5-5 weeks for 16 patients. Local control (LC) was obtained in 27 out of 31 patients (87%), with a minimal follow-up duration of 2 years. Eleven out of 31 patients died: seven with local control (one from an intercurrent disease, six from distant metastasis) and four with local failure inside the IORT fields. Twenty patients are alive with no evolutive disease in 19 cases and with a distant metastasis in one case.(ABSTRACT TRUNCATED AT 250 WORDS)