The value of postoperative radiation therapy (RT) was investigated in 77 patients with esophageal cancer resected between 1977 and 1986. Surgical resection was palliative in 13 of these patients. Although seven of them underwent postoperative irradiation to the residual tumor, all of the patients died within one year. Following potentially curative resection performed in 64 patients, 31 patients received 50 Gy of postoperative RT to the lower neck and the mediastinum (group Ia), seven were unable to receive full-dose postoperative RT (group Ib), and 26 were not treated with postoperative RT (group II). The 5-year survival rate estimated by the Kaplan-Meier method was 54% for group Ia, 29% for group Ib, and 33% for group II, with the difference between groups Ia and II being significant (p less than 0.025). The local recurrence rate in the mediastinum was lower in group Ia than in group II. Prophylactic postoperative RT for esophageal cancer is a safe and effective regimen for patients with resected disease.