 BACKGROUND CLINICAL SIGNIFICANCE Barretts Esophagus the pre-malignant lesion for esophageal adenocarcinoma - a Condition of Rapidly Increasing Incidence. Patients with BE are at an increased risk for the development of esophageal adenocarcinoma and esophagogastric junction adenocarcinoma. Adenocarcinoma of the esophagus is believed to arise from BE in a step-wise progression from low-grade dysplasia to high-grade dysplasia, finally leading to frank adenocarcinoma 4,5. The cost effectiveness of surveillance endoscopy in patients with BE is very sensitive to the incidence of cancer 11. The exact incidence of adenocarcinoma in patients with BE is not known and has been reported to vary from 1 in 50 patient-years of follow up to 1 in 285 patient-years of follow up 18-22. The published incidence data from existing cohorts of patients with BE have been influenced by the small number of patients being evaluated, short duration of follow-up as well as by the demographics of the population being studied e.g. older patients, male sex. To date, the maximum number of patients included in a published study determining the incidence of adenocarcinoma has been only 327 patients 23,24. The ultimate goal of the proposed study is to establish a large cohort of patients with BE to address issues of incidence, progression and risk factors influencing progression. Such an approach was recently endorsed by the NIH 2002 PRG on stomach and esophageal cancers. 