Seventy-two patients with a carcinoma of the head and neck, who were treated with surgery and postoperative irradiation, were reviewed to determine the local recurrence rates and survival in patients with inadequate surgical margins. Tumor recurrence rate was 31% for patients with microscopic tumors at resection margins and 50% for those with macroscopic tumor. Actuarial 3-year survival for these patients was 71% and 43%, respectively. All 4 patients who were irradiated later than 6 weeks after surgery developed recurrent malignancy despite the resection margins being free of tumor. Excluding these patients the 3-year survival for R0 patients was similar to that of R1 patients. It is concluded that postoperative irradiation is effective in patients with tumor at the surgical margins. It is suggested that the time interval between surgery and radiation therapy be limited to less than 6 weeks. Radiation dose prescriptions for various clinical situations are discussed.