 This study evaluates PGE2 production, COX-2 enzyme activity and PCNA expression in Barretts metaplastic tissue. All patients will have a baseline endoscopy with multiple biopsies. The patients will then be receive four dosing regimens esomeprazole, esomeprazole and aspirin, esomeprazole and rofecoxib, or rofecoxib alone consecutively each for a 10 day dosing period, whilst undergoing further follow up endoscopies and multiple biopsies. 