Associations between alcohol drinking and cardiovascular disease mortality could be confounded by diet if alcohol drinking and diet are related. Depending on the alcohol measure, alcohol-diet relations may or may not be observed. The authors examined associations between alcohol and diet quality (Healthy Eating Index (HEI) scores) using cross-sectional, nationally representative data from the 1999-2000 National Health and Nutrition Examination Survey. Weighted analyses included 3,729 participants aged > or =20 years. In adjusted analyses among current alcohol drinkers, as quantity increased from 1 to > or =3 drinks/drinking day, the mean HEI score decreased from 65.3 (95% confidence interval (CI): 63.4, 67.1) to 61.9 (95% CI: 60.5, 63.2). As frequency increased from the lowest quartile to the highest, the mean HEI score increased from 60.9 (95% CI: 58.7, 63.2) to 64.9 (95% CI: 63.4, 66.4). As average volume ((quantity x frequency)/365.25) increased from <1 drink/day to > or =3 drinks/day, the mean HEI score increased from 62.9 (95% CI: 61.2, 64.5) to 65.2 (95% CI: 62.7, 67.8). In stratified analyses, the lowest HEI score, 58.5 (95% CI: 55.5, 61.5), occurred among drinkers who consumed the highest quantity at the lowest frequency. Average volume of alcohol consumed is driven by and masks the contributions of its components. These results suggest the importance of measuring drinking patterns (quantity, frequency, and stratified combinations) in epidemiologic alcohol-diet studies.