BACKGROUND: Because high dietary and blood n-3 (omega-3) fatty acids (FAs) are protective against coronary heart disease and sudden cardiac death, the alcohol-associated increase in blood n-3 FAs could be considered an original mechanism of alcohol's cardioprotective effect. OBJECTIVE: Our objective was to assess whether alcohol consumption is associated with concentrations of very-long-chain "marine" (eg, fish oil) n-3 FAs both in plasma and in red blood cell membranes. DESIGN: In the framework of the IMMIDIET (Dietary Habit Profile in European Communities with Different Risk of Myocardial Infarction: the Impact of Migration as a Model of Gene-Environment Interaction) Project, 1604 subjects (802 women-men pairs), aged 26-65 y, were enrolled in Italy, Belgium, and England. A 1-y-recall food-frequency questionnaire was used to evaluate dietary intake. RESULTS: In fully adjusted multivariate analyses, alcohol intake was positively associated with plasma eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and EPA + DHA concentrations (P < 0.0001, P = 0.036, and P = 0.002, respectively) in women and with EPA and the EPA + DHA index in red blood cells (P < 0.0001 and P = 0.037, respectively). In men, only plasma and red blood cell EPA concentrations were associated with alcohol intake (P = 0.003 and P = 0.004, respectively). Stratified analyses showed an association between alcohol and both plasma and red cell EPA (P = 0.008 and P = 0.002, respectively), DHA (P = 0.014 and P = 0.008, respectively), and the EPA + DHA index (P = 0.010 and P = 0.006, respectively) in wine drinkers, whereas no association was found in those who drink beer and spirits. CONCLUSIONS: Alcohol intake was associated with higher plasma and red blood cell concentrations of marine n-3 FAs. Components of wine other than alcohol (polyphenols) might exert these effects. Part of the alcohol-induced cardioprotection may be mediated through increased marine n-3 FAs.