An association between heavy alcohol drinking and gastric cancer risk has been recently reported, but the issue is still open to discussion and quantification. We investigated the role of alcohol drinking on gastric cancer risk in the “Stomach cancer Pooling (StoP) Project”, a pooled analysis of case-control studies. A total of 9,669 cases and 25,336 controls from 20 studies from Europe, Asia and North America were included. We estimated summary odds-ratios (ORs) and the corresponding 95% confidence intervals (CIs) by pooling study-specific ORs using random-effects meta-regression models. Compared with abstainers, drinkers of up to 4 drinks/day of alcohol had no increase in gastric cancer risk, while the ORs were 1.26 (95% CI, 1.08-1.48) for heavy (>4 to 6 drinks/day) and 1.48 (95% CI 1.29-1.70) for very heavy (>6 drinks/day) drinkers. The risk for drinkers of >4 drinks/day was higher in never smokers (OR 1.87, 95% CI 1.35-2.58) as compared to current smokers (OR 1.14, 95% CI 0.93-1.40). Somewhat stronger associations emerged with heavy drinking in cardia (OR 1.61, 95% CI 1.11-2.34) than in non-cardia (OR 1.28, 95% CI 1.13-1.45) gastric cancers, and in intestinal-type (OR 1.54, 95% CI 1.20-1.97) than in diffuse-type (OR 1.29, 95% CI 1.05-1.58) cancers. The association was similar in strata of H. pylori infected (OR=1.52, 95% CI 1.16-2.00) and non-infected subjects (OR=1.69, 95% CI 0.95-3.01). Our collaborative pooled-analysis provides definite, more precise quantitative evidence than previously available of an association between heavy alcohol drinking and gastric cancer risk. This article is protected by copyright. All rights reserved.