This study was carried out to determine whether locoregional control of nasopharyngeal carcinoma in the young by irradiation has improved since 1975. Fifty-seven consecutive, previously untreated, patients, less than 30 years old, were diagnosed and treated at University of Toronto Hospitals between 1958 and 1990; 21 patients were treated before and 36 after 1975. Staging was as follows: M0, n = 54; M1, n = 3; T1 + T2, n = 26; T3 + T4, n = 31; N0, n = 10; N1 + N2a, n = 10; N2b + N2c, n = 24; N3, n = 13. All patients were irradiated. The primary tumour dose was 3500-7000 cGy (median 5450). Adjuvant chemotherapy was introduced in 1977. Subsequently, 10/26 (38%) M0 patients received this treatment. For all 57 patients, 10-year survival was 56%. For 52 M0 patients with complete follow-up data, 10-year survival was 63%; 10-year relapse free survival (RFS) was 61%. Age, sex, race, and histology were not significant variables. Ten-year RFS results were: T1 + T2, M0 (n = 24) 70%, T3 + T4, M0 (n = 27) 52%, (P = 0.25); N0-N2c (n = 41) 64%, N3 (n = 11) 54% (P = 0.31). Relapse occurred in 20/52 (38%) patients. Survival from the date of first relapse was 10% at 10 years. No patient with systemic relapse survived. Only 1/32 (3%) patients treated after 1975 developed an isolated locoregional relapse, giving a 10-year isolated locoregional relapse free rate (LR RFS) of 96%, compared with 5/20 (25%) prior to 1975, which gave a 10-year LR RFS of 75% (P = 0.05). Two of the five patients who relapsed before 1975 were salvaged by re-irradiation. Systemic relapse, either alone or combined with locoregional relapse, accounted for 6/11 (55%) relapses before 1975 and 8/9 (89%) after 1975. Ten-year systemic RFS was 90% for patients who received adjuvant chemotherapy (n = 10) and 72% for patients treated since 1977 by irradiation alone (n = 16) (P = 0.41). Isolated local relapse was exceptional in patients treated after 1975 (1/32).(ABSTRACT TRUNCATED AT 250 WORDS)