Helicobacter pylori (HP) is associated with chronic gastritis and gastric cancer, and more than half of the world's population is chronically infected. The aim of this retrospective study was to investigate whether an irregular meal pattern is associated with increased risk of gastritis and HP infection. The study involved 323 subjects, divided into three groups as follows: subjects with HP infection and gastritis, subjects with gastritis, and a control group. Subjects were interviewed on eating habits and meal timing. Multivariate logistic regression was used to compare groups. Adjusted odds ratios (OR) were derived controlling for gender, age, stress, and probiotic consumption. Subjects who deviated from their regular meals by 2 hours or more had a significantly higher incidence of HP infection with gastritis (adjusted OR = 13.3; 95% CI 5.3-33.3; P < 0.001) and gastritis (adjusted OR = 6.1; 95% CI 2.5-15.0; P < 0.001). Subjects who deviated their meals by 2 hours or more, twice or more per week, had an adjusted OR of 6.3 and 3.5 of acquiring HP infection with gastritis (95% CI 2.6-15.2; P < 0.001) and gastritis (95% CI 1.5-8.5; P < 0.001), respectively. Frequent deviation in meal timing over a prolonged period appears associated with increased risk of developing HP infection and gastritis.