The present study was conducted to evaluate the therapeutic results of alternating chemoradiotherapy for locally advanced nasopharyngeal cancer. The subjects were 87 patients with stage II-IVB nasopharyngeal cancer. Alternating chemoradiotherapy was performed; initially, chemotherapy was administered, and then radiotherapy (wide field), chemotherapy, radiotherapy (shrinking field), and chemotherapy were alternately performed. For chemotherapy, 5-FU at a dose of 800 mg/m2/24 h was intravenously administered for 5 days (days 1-5), and CDDP at a dose of 50 mg/m2/24h for 2 days was administered on day 6 and 7. The scheduled courses of alternating chemoradiotherapy were completed in 70 (80%) of 87 patients. Although 1 patient developed a transient neurological disturbance induced by hyper-ammonemia by metabolism of 5-FU, no severe adverse effects were noted in any other patients. In these 87 patients, the overall 5-year survival rate was 83% (95% confidence interval: 74-92%), and the progression free survival rate was 75% (95% CI: 66-85%). This method of alternating chemoradiotherapy yielded higher or at least similar survival rates and lower toxicities than concurrent chemoradiotherapy, and is worth trying in a randomized controlled study to compare with concurrent chemoradiotherapy.