This study presents a retrospective analysis of a consecutive series of 161 patients treated with curatively intended radiotherapy for T1 supraglottic or glottic carcinoma from 1972 to 1990 at the Department of Oncology, Aalborg County Hospital, Denmark. All patients received radiotherapy given with 4-MV X-rays on lateral opposed fields. Intended dose was 60 Gy in 30 fractions. Multivariate analysis of recorded clinical parameters was applied to identify possible prognostic factors of local control. Tumor size, differentiation grade and sex were identified as significant independent prognostic parameters of local control. Five-year local control was 58% and 78% for supraglottic and glottic tumors, respectively. Applying salvage surgery the ultimate control rates were 82% and 97% for supraglottic and glottic tumors, respectively. Evaluation of treatment response 3-6 weeks following accomplishment of radiotherapy demonstrated that remaining tumor at the time of evaluation was an indicator of failure in local control.