BACKGROUND: We would like to evaluate the prognostic significance of young age (defined as 50 years old or less) for tonsillar carcinoma because of its association with HPV 16 virus infection. MATERIALS AND METHODS: Data were extracted from the SEER database for 5535 patients aged 22-99 years (median 58) diagnosed with squamous cell carcinoma of the tonsil between 1974 and 2003. Primary therapy included radiotherapy for 4494 patients, and surgery for 3018 patients. Cox proportional hazard models were used for cancer-specific survival (CSS) analysis adjusting for demographic characteristics, tumor stage, and local therapy. Subgroups were compared using interaction tests. RESULTS: The incidence of tonsil carcinoma increased at a faster pace in young patients, from 15% in 1974-1983 to 55% in 1994-2003, compared with an increase from 26% to 37% in older patients. The 5- and 10-year CSS were 74% and 67%, 59% and 46% for young and older patients, respectively. In multivariate analysis, young age was independently associated with 40% relative better CSS compared with older age, hazard ratio 0.60 (95% confidence interval 0.54-0.67). CONCLUSION: Young age is associated with an excellent prognosis most likely related at least in part to a higher incidence in this age group of HPV-associated tumors, possibly with increased tumor sensitivity to radiation. Prospective studies on oropharyngeal cancers should be performed to confirm this hypothesis.