Female college students (n = 49) from a small southwestern United States university participated in the 9-month study. Data collected included the assessment of drinking habits and other related substance use habits and serum levels of carbohydrate-deficient transferrin (CDT). Each subject provided an interview and blood sample on three occasions at 90-day intervals. Appended to the interview were a series of questions regarding stage of menstrual cycle and the diagnoses of certain diseases. The CDT values obtained were consistent with those obtained in other studies. Moderate-drinking subjects had significantly higher CDT values than did the abstainers and light drinkers. Females using oral contraceptives had significantly higher CDT values than those who were not taking oral contraceptives. Finally, although CDT values varied over time, they did not appear to vary as a function of menstrual cycle stage.