Intra-arterial chemotherapy from bilateral superficial temporal arteries and radiotherapy were carried out preoperatively on two patients with oral cancer on the midline. Total doses of preoperative chemo- and radio-therapies were 160 mg/m2 of carboplatin, 50 mg of peplomycin and 20 Gy of 60Co-irradiation, respectively. Therapeutic effect of preoperative chemo- and radio-therapies was evaluated on the resected materials from histological point of view. In case 1, the effect was judged as Grade II A in Oboshi's classification, which indicated a mild destruction of architecture of tumor tissue and a few viable tumor cells, but an extreme reduction of the primary lesion was observed on clinical appearance. In case 2, the therapeutic effect was regarded as Grade II B, which indicated a severe destruction of architecture of tumor tissue and few viable tumor cells. Concerning toxicity, mucositis and slight thrombocytopenia (96,000/mm3) in case 1, and mucositis and leukopenia (2,300/mm3) in case 2 appeared. However, they soon recovered after termination of the preoperative therapies. From the above results, it was considered that a combination of bilateral intra-arterial chemotherapy and radiotherapy was quite effective as a preoperative treatment for oral cancers on the midline at the same doses of anti-neoplastic agents and irradiation as for the other unilateral oral cancers.