Patients with Barrett's esophagus are recognized as having a high risk of development of adenocarcinoma. Although endoscopic surveillance of these patients is commonly practiced, its benefits have not been proved. This study was undertaken to examine the effect of endoscopic surveillance on the stage of resected carcinoma arising in Barrett's esophagus and the effect on postoperative survival. Between 1973 and 1991, 77 patients with adenocarcinoma were seen by us, and 19 of them were under endoscopic surveillance. The 19 patients underwent endoscopic biopsies at 1-month to 4-year intervals (median 6 months). All but one patient underwent esophagogastrectomy when severe dysplasia or invasive carcinoma was detected. The stages of the resected carcinomas in the group under surveillance compared with the group not under surveillance were significantly different, 58% of the patients under surveillance having stages 0 and I disease and 21% having stage III disease compared with 17% of the patients not under surveillance having stages 0 and I disease and 47% having stage III disease (p = 0.006). The 5-year actuarial survival of patients undergoing routine surveillance was 62% and of patients not under surveillance, 20% (p = 0.007). Endoscopic surveillance of patients with benign Barrett's esophagus permits detection of carcinoma at an early stage and improves long-term survival after resection for severe dysplasia and invasive carcinoma.