197 patients, with an early glottic cancer, were heated with radiotherapy at the Institute Gustave Roussy, between 1970 and 1983. Radiation was delivered up to a dose of 65 Gy over 6 1/2 weeks on a small area centered on the glottic region. All patients had previously undergone direct laryngoscopy and showed T1 stage tumours (175 T1a and 22 T1b) although in 32 cases there was a suspicion of very limited involvement of the ventricle or sub-glottis. 5 year survival for the overall population was 77.5%. 38 local recurrences were observed, 1/4 of these occurring after 3 years. For the overall population, local control at 5 years was 85.7%. Suspicion of supra or sub-glottic involvement and the presence of impaired mobility of the larynx were shown to be important prognostic factors. Local control at 5 years was 90% for "true T1" cases. Few complications were observed and the functional results of irradiation were judged to be excellent.