The aim of the present study was to determine the frequency and amount of chili taken by peptic ulcer patients and control subjects. One hundred three Chinese patients with peptic ulcer and 87 control patients were interviewed using a standard questionnaire. Those subjects who deliberately avoided chili use because of symptoms or advice from friends or medical practitioners were excluded. The median number of times of chili use per month was eight in the ulcer group (25-75% quartiles 1-30) compared to 24 (8-56) in the control group (P < 0.001). The median amount of chili used per month was 312 units (25-75% quartiles 38-899) in the ulcer group compared to 834 units (274-1892) in the control group (P < 0.001). The odds ratio of having peptic ulcer disease, adjusted for age, sex, analgesic use, and smoking by multiple logistic regression, was 0.47 (95% confidence intervals: 0.25-0.89) for subjects who had a higher intake of chili both in terms of frequency as well as amount used compared to those who took less chili. Our data support the hypothesis that chili use has a protective effect against peptic ulcer disease.