OBJECTIVE: Heavy alcohol drinking is associated with increased prevalence of systemic hypertension (HTN), but the relationship between moderate drinking and HTN remains unclear. We explored the possible role of underreporting among moderate drinkers. METHOD: In a cross-sectional analysis of 105,378 persons, we defined a subset among persons reporting three or fewer drinks per day that was likely to include a disproportionate number of underreporters. This subset included persons who, on another occasion, indicated intake of three or more drinks per day or who ever had a diagnosis of an alcohol-related condition; these persons are called ‘positive.’ Persons who never reported three or more drinks per day and who had no alcohol-related diagnosis were called ‘negative.’ Logistic regression models estimated the odds ratios (ORs) for prevalent HTN (140/90 mm Hg or greater) in the positive and negative subgroups, compared with lifelong abstainers as referent. All persons and four race-gender groups were studied, and they were controlled for age, education, smoking, and body mass index. We also studied the relationship of blood liver transaminase enzyme levels in the positive and negative subgroups at specific alcohol intake strata. RESULTS: For persons reporting one to two drinks per day, the OR (95% confidence interval) of HTN was 1.32 (1.21-1.43) for positive persons and 1.16 (1.09-1.25) for negative persons. For those reporting less than one drink per day, the ORs were 0.97 (0.89-1.06) for positives and 0.92 (0.87-0.98) for negatives. For those reporting one to two drinks per day, positive/negative comparisons showed approximately a 75% increased prevalence of high liver transaminase enzymes. For those reporting less than one drink per day, the positive/negative difference was approximately 30%. CONCLUSION: In these data, increased prevalence of HTN among persons reporting one to two drinks per day appears to be partially due to underreporting of alcohol intake.