In order to improve the efficacy of endoscopic surveillance of Barrett's esophagus, markers of neoplastic progression in addition to dysplasia are required. The aim of the present study was to assess TP53 mutational analysis as a method of identifying patients with Barrett's esophagus who are at greatest risk of adenocarcinoma, for whom endoscopic surveillance is most appropriate. TP53 mutational analysis was initially performed on premalignant and malignant tissue from 30 patients undergoing esophagectomy for adenocarcinoma, and on premalignant biopsies from 48 patients participating in a Barrett's surveillance program. Surveillance patients were followed up endoscopically and histologically for a median of 5 years following TP53 assessment. Mutational analysis was performed by single-strand conformation polymorphism analysis and direct DNA sequencing. TP53 mutations were detected in 10 of 30 esophageal adenocarcinomas, and were more common in well-differentiated carcinomas. An identical TP53 mutation was detected in carcinoma and adjacent dysplasia. Two patients with premalignant Barrett's esophagus had TP53 mutations and one of these patients developed adenocarcinoma on follow up whilst the other has not yet progressed beyond metaplasia. No patient without TP53 mutation developed high-grade dysplasia or adenocarcinoma. TP53 mutations are detected in 33% of esophageal adenocarcinomas and in 4% of premalignant Barrett's esophagus in patients undergoing endoscopic surveillance. TP53 mutation can be detected before the development of high-grade dysplasia or carcinoma, and may be useful in stratifying the risk of adenocarcinoma in patients with Barrett's esophagus.