One-hundred eighteen patients with previously untreated T3 squamous cell carcinoma of the glottic larynx were treated with curative intent between March 1965 and November 1988 at the University of Florida. All patients were observed for at least 2 years and 83% were observed for 5 or more years. Fifty-three patients were treated with irradiation alone and 65 patients were treated with surgery alone (32) or combined with irradiation (33). Thirty-two patients treated with irradiation alone had twice-daily fractionation and the remainder had once-daily fractionation. The local-regional control rates, including patients successfully salvaged after a local-regional recurrence, were 81% after irradiation alone and 81% after surgery alone or combined with adjuvant irradiation. The local control rates for patients treated with irradiation alone were 53% after once-daily fractionation and 71% after twice-daily fractionation. There was no relationship between vocal cord mobility at 5000 cGy, at the end of radiotherapy, or at 1 month after treatment and subsequent local control. The 5-year cause-specific survival rates were 74% for patients treated with irradiation alone and 63% for patients treated surgically. The incidence of severe complications, including those associated with salvage procedures, was 15% for both treatment groups. The rates of laryngeal voice preservation were 66% after irradiation alone and 2% after surgery. Irradiation alone for selected patients with T3 glottic cancer resulted in similar rates of local-regional control, survival, and severe complications, with a significantly higher likelihood of voice preservation, compared with surgery.