In this study, the radiation sensitizer effect of epirubicin, an analogue of adriamycin, used as concomitant continuous infusion with hyperfractionated radiotherapy was investigated prospectively in the treatment of unresectable soft tissue sarcomas. On the evaluation done 3 months after the end of treatment in 8 patients, nearly complete response in 1 patient and partial responses in 7 patients were obtained. Surgical resection (wide local excision) was performed in 5 of 7 patients in whom the tumor masses became resectable after the treatment. Pathological examination of the surgical specimens showed fibrosis only in 1 patient, necrosis over 90 % in 2 patients and over 80% in 2 patients.