The optimum postoperative dose for local or regional disease control was retrospectively assessed in 70 patients with head and neck cancer given adjuvant external beam radiotherapy. Actuarial 2-year survival rates with no evidence of disease (NED) according to stage were 75%, 59%, and 72% for stages II, III, and IV, respectively. Primary tumor/regional failure and distant metastasis adversely affected prognosis. Patients had an actuarial 2-year NED of 80% when the dose to the primary tumor/upper neck was greater than or equal to 60 Gy but was 53% when the dose was less than 60 Gy. Two-year NED was 85% in those patients given greater than 50 Gy to the lower neck and 62% when less than or equal to 50 Gy was used. Based on these results, a total dose of at least 60 Gy to the primary tumor bed and upper neck and greater than 50 Gy to the lower neck whenever adjuvant postoperative irradiation is administered for subclinical disease is recommended.