Background and Objectives: H. pylori are an accepted cause of chronic active gastritis and commonly associated with both gastric and duodenal ulcer. Moderate to severe gastritis increases the relative risk of developing peptic ulceration and eradication of the bacteria reduces duodenal ulcer recurrence. The effect of H pylori on the duodenal brush border membrane enzymes have not been studied extensively in this infection. This study evaluates the duodenal brush border enzymes between the H. pylori positive and negatives patients. Design, setting, participants & measurements: One hundred and nine patients, age range 20-84 years, mean age 56 years were included in the study. They presented to the endoscopy suite of UCHG with upper gastrointestinal symptoms. The duodenal bulb was entirely normal and with no evidence of inflammation on endoscopic examination. Biopsies from the antrum were processed for histology and bacteriological culture. Two biopsies from the duodenal bulb were taken from each patient and were sealed in Para-film and stored at -20C0 until assayed for brush border enzymes.