This retrospective study, based on a series of 90 patients with invasive squamous cell carcinoma of the supraglottis, was designed to document the functional outcome and complications after postoperative radiation therapy following partial laryngeal surgery. The surgical procedure was a standard supraglottic laryngectomy in 62 patients and a supracricoid partial laryngectomy in 28 patients. All of the patients had an unremarkable postoperative course and achieved locoregional control. The average dose delivered to the remaining larynx was 51.2 Gy (range 25-71 Gy). The average dose delivered to the neck was 50.6 Gy (range 2270 Gy). The patients were treated at 180-cGy per fractions in a continuous course technique with a cobalt 60 beam. In 5 patients (5.5%) complications led to cessation of postoperative radiation therapy, and the total dose delivered to the remaining larynx and neck was less than 40 Gy. All patients were followed up for a minimum of 10 years or until death. The 5-, 10-, and 15-year actuarial survival estimates were 71.5%, 44.3%, and 36.3%, respectively. The 5-, 10-, and 15-year actuarial severe complication estimates were all 11.2%. Overall, severe complications occurred in 15 patients. Severe complications led to death in 3 patients (3.3%), permanent gastrostomy in 3 (3.3%), and permanent tracheostomy in 1 (1.1%). A severe complication never resulted in completion of total laryngectomy. In univariate analysis, the mean dose delivered to the larynx was the only variable statistically related to the incidence of a severe complication. The mean dose delivered to the larynx was statistically higher ( P = 0.014) in patients who had severe complications (60 Gy) than in patients who did not (50 Gy).