The authors previously have found that in patients with locally advanced squamous cell carcinoma of the head and neck (SCC-HN), alternating chemoradiotherapy (ALT) was superior to low-total-dose conventional radiotherapy alone. The purpose of this randomized trial was to compare the same chemoradiotherapy approach with high-total-dose partly accelerated radiotherapy. During 6 years, 136 consecutive patients with previously untreated unfavorable Stage II or Stage III-IV (International Union Against Cancer) SCC of the oral cavity, pharynx, and larynx were enrolled. They were randomly assigned to chemotherapy consisting of 4 cycles of intravenous cisplatin (20 mg/m(2) of body surface area per day for 5 consecutive days) and 5-fluorouracil (200 mg/m(2) per day for 5 consecutive days; weeks 1, 4, 7, and 10) alternated with three 2-week courses of radiotherapy (20 grays Gy per course, 2 Gy per day, 5 days per week; ALT, 70 patients) or to partly accelerated radiotherapy with final concomitant boost technique (75 Gy/40 fractions in 6 weeks; partly accelerated radiotherapy PA-RT, 66 patients). At the median follow-up of 60 months (range, 30-102 months), no statistical differences were observed in overall survival, progression free survival, or locoregional control between the 2 treatments. Actuarial 3-year overall survival and progression free survival were 37% and 35%, respectively, in the ALT group and 29% and 27%, respectively, in PA-RT group. The median overall survival and progression free survival were 24 and 15 months, respectively, in the ALT arm and 18 and 11 months, respectively, in PA-RT arm. Actuarial 3-year locoregional control rates were 32% in the ALT group and 27% in the PA-RT group. At multivariate analysis, tumor classification was the only factor that emerged as a significant independent variable affecting overall survival. Patients treated in the PA-RT arm experienced higher Grade 3+ (World Health Organization) acute skin and mucosal reactions than patients in the ALT arm. Moreover, local late mucosal and skin toxicities occurred more often in patients treated with PA-RT. This trial failed to disclose statistically significant differences in the outcome of patients treated with either ALT or PA-RT. Therefore, definitive conclusions could not be made. However, acute skin effects and late mucosal and skin toxicities above the clavicles appeared to be significantly lower with chemoradiotherapy.