Few studies have assessed the relation between dietary patterns and gastric adenocarcinoma risk, yet this approach has advantages over single-nutrient analysis, including the ability to reflect eating patterns in populations and ease of implementing dietary recommendations. The authors evaluated associations between dietary patterns, a food index score, and incident gastric cancer risk in a Canadian study of 1,169 cases and 2,332 controls (1995-1997). Dietary patterns were assessed via factor analysis applied to a food frequency questionnaire. A food index score was derived based on risk factors for gastric cancer. A multivariable-adjusted prudent dietary pattern was associated with decreased risk of gastric cancer in women (odds ratio (OR) = 0.58, 95% confidence interval (CI): 0.37, 0.92); a Western dietary pattern was associated with increased risk in women (OR = 1.86, 95% CI: 1.20, 2.89) and men (OR = 1.44, 95% CI: 1.03, 2.02). The food index score was associated with decreased risk among women (OR = 0.40, 95% CI: 0.27, 0.59) and men (OR = 0.63, 95% CI: 0.45, 0.88). Dietary patterns especially characterized by Western features (soft drinks, processed meats, refined grains, and sugars) were associated with increased risk of gastric adenocarcinoma, whereas dietary patterns characterized by increased consumption of fruits, vegetables, and fish were associated with lessened risk.