We examined the association between alcohol and caffeine consumption and premenstrual syndrome (PMS). One hundred two women with PMS matched by age and race to an equal number of women without PMS were compared for differences in intake of alcoholic and caffeinated beverages, with differences determined using Student's t-tests and conditional logistic regression for matched pairs. Information on alcohol and caffeinated beverage consumption was obtained from three 24-hour dietary recall interviews conducted during the postmenstrual period and from three conducted during the premenstrual period. Results showed that no significant difference was observed in total caffeine intake or in the individual caffeinated beverages consumed during either the post-menstrual or the premenstrual period. For alcohol consumption, however, women with PMS drank 1.41 (95% confidence interval; range, 0.34-2.47) more servings per week during the postmenstrual period. Based on post-menstrual consumption, women in the heaviest drinking category (> or = 10 drinks per week) were significantly more likely to have moderate to severe PMS (P < .005) than nondrinkers. This same significant relation, but to a lesser degree, was observed based on premenstrual consumption. We conclude that because PMS is more strongly associated with alcohol consumed in the symptom-free, postmenstrual period, drinking is unlikely to be simply a response to PMS symptoms as others have previously suggested.