An analysis of 129 patients with 131 squamous cell carcinomas of the supraglottic larynx treated between October 1964 and April 1987 with radiotherapy alone or radiotherapy followed by neck dissection is presented. All patients had a minimum 2-year follow-up. Patients were excluded from analysis of disease control at the primary site and/or neck if they died within 2 years of treatment with the site(s) continuously disease-free. Local control rates with radiotherapy and ultimate local control rates, including patients successfully salvaged after a local recurrence, were as follows: T1, 13 of 13 and 13 of 13; T2, 34 of 42 (81%) and 37 of 42 (88%); T3, 25 of 41 (61%) and 34 of 41 (83%); and T4, 3 of 9 and 6 of 9. There was no significant difference in local control rates when comparing patients who were anatomically suitable for a supraglottic laryngectomy with those who would have required a total laryngectomy. Local control rates were slightly diminished in patients with T2-T3 lesions who had impaired or absent vocal cord mobility. The overall rates of ultimate local control with voice preservation for the entire series of 129 patients were as follows: T1, 100%; T2, 87%; T3, 69%; and T4, 57%. Cause-specific survival rates at 5 years by stage were I, 2 of 2; II, 10 of 12 (83%); III, 9 of 13 (69%); IVA, 4 of 6; and IVB, 7 of 22 (32%). The incidence of severe complications was 4 of 115 (3%) for T1-T3 lesions and 4 of 14 (29%) for T4 lesions.