We undertook a cross-sectional study in 107 premenopausal women in Maryland (United States) of alcohol intake and hormonal status in order to evaluate whether plasma hormone levels might mediate the reported positive relation between alcohol ingestion and breast cancer risk. Alcohol ingestion was estimated using a drinking pattern questionnaire, a food frequency questionnaire, and seven-day food records. Fasting blood specimens were collected on days 5-7, 12-15, and 21-23 of each participant's menstrual cycle and pooled to create follicular, midcycle, and luteal phase samples, respectively, for analysis. Estrone, estrone sulfate, estradiol, androstenedione, and dehydroepiandrosterone sulfate (DHEAS) in plasma were measured by radioimmunoassay, and sex-hormone binding globulin (SHBG) was measured by an immunoradiometric assay. After adjusting for age, weight, and total energy intake, alcohol ingestion was not associated with plasma estrogens in the follicular, midcycle, or luteal phases of the menstrual cycle, nor with the level of SHBG or DHEAS in plasma averaged from the three phases of the cycle. Alcohol, however, was significantly positively associated with the average level of plasma androstenedione. Based on these cross-sectional findings among premenopausal women, the increased risk of breast cancer related to alcohol ingestion does not appear to be mediated by elevated plasma estrogen levels. Androstenedione, however, may mediate the alcohol/breast cancer-association.