Between May 1980 and October 1982, 25 patients with esophageal carcinoma were treated with a high dose rate, remote-controlled afterloading unit as a booster therapy for the intracavitary irradiation following external irradiation. All patients were observed in a follow up program which continued for more than 1 year after the beginning of radiation treatment. As of August 1983, 7 patients were alive and had had no local recurrence. Eighteen patients had died, of whom 9 had local failure. Local control rates at 6 months and 1 year were 67.3% and 62.1% respectively, which were significantly better than those in the group treated with external irradiation alone (p less than 0.01). Side effects were seen in 12 patients, but no special treatment was necessary. As for complications, esophageal ulcers were found in 24 patients, who, except for 2 patients, were all cured by conventional treatment. Other complications were 5 cases of stricture, 4 of esophago-bronchial fistula, 1 of esophago-aortal fistula, 1 of pulmonary fibrosis, and 1 of radiation osteitis. No radiation myelitis occurred.