"BAR" therapy is a combined therapy with BUdR (Radiosensitizer), Antimetabolites (5-FU, FT-207 etc.) and Radiation for malignant tumours. How radiation can be reduced as far as possible and how the effects of treatment can be increased as much as possible are the objectives of this study of combining radiation and BUdR therapy. The authors attempted to irradiate 3-5 days after the BUdR and antimetabolite had been infused via the superficial temporal artery, in 12 malignant oral tumours (11 squamous cell carcinomas and 1 reticulum-cell sarcoma). BUdR 50-250 mg/day, antimetabolites (5-FU) 10-250 mg/day and a total irradiation dose of 6000 rads by 6 MeV Linac X-ray or Co-60 gamma ray, 200 rads/day were given. 9 marked responses, 2 moderate responses and 1 no response (2 cases were operated on by local resection) were obtained by the authors. Side effects of treatment were observed during the course of "BAR" therapy. Stomatitis was found in all patients and it occurred on the mucosa of the tumour-affected site especially. Dermatitis of the skin of the face was noted in 6 cases, resembling irradiation dermatitis. Fever was observed in 4 cases and it always occurred after irradiation. Diarrhoea was noted in 3 cases and occurred before irradiation, 2 out of 3 were given BUdR 0.1 g and the remaining one was given BUdR 1 g, and 5-FU lg. In addition, there were: 1 loss of appetite, 1 nausea and 1 exfoliation of nails.