To evaluate the usefulness of chemoradiotherapy for oropharyngeal cancer, we retrospectively analyzed disease-free survival (DFS) and acute toxicities of the patients treated with this therapy. Between 1990 and 1998, 15 patients were treated with alternating chemoradiotherapy (CRT). Chemotherapy (CT) mainly consisted of 5-fluorouracil 700 mg/m2 (i.v.) on days 1-5 and nedaplatin 100-140 mg/m2 (i.v.) on day 6. Chemotherapy was administered before the beginning of radiotherapy. One cycle of this treatment consisted of CT and a subsequent 27 to 36 Gy of radiotherapy, as a general rule, two cycles were performed. Radiotherapy was delivered in single daily fractions of 1.8 to 2 Gy, to a total dose of 54 to 75 Gy for local lesions and 45 to 86.3 Gy for nodal metastases in the neck. As a historical control, 52 patients treated with curative radiotherapy between 1971 and 1990 were analyzed and compared with the CRT group in terms of DFS. The complete response rate with CRT was 100%. The three-year DFS were 87% and 38% with CRT and RT, respectively. There was a significant difference between the two groups (p = 0.0081). The most frequent and severe acute toxicity was mucositis, with grade 3-4 occurring in 47%. Acute hematologic toxicities were mild. Therefore, this CRT is considered to be an effective and tolerable treatment, and is expected to improve survival for oropharyngeal cancer patients.