Objective: To examine the effects of alcohol, caffeine, and tobacco use on early follicular phase FSH, LH, E 2 , and sex hormone-binding globulin (SHBG).Design: Cross-sectional study.Setting: Academic medical center.Patient(s): Four hundred ninety-eight women selected from the general population, ages 36–45, who were not currently pregnant, breast feeding, or using exogenous hormones.Intervention(s): A general questionnaire assessing demography, anthropometry, and smoking habits and a standardized dietary questionnaire assessing food and beverage frequencies, including sources of alcohol and caffeine.Main Outcome Measures: FSH, LH, E 2 , and SHBG levels measured during the early follicular phase of the menstrual cycle.Result(s): Significant associations observed in a univariate analysis included age ≥40 and current smoking associated with higher FSH; higher body mass index (BMI) associated with lower SHBG levels; and daily alcohol use, cholesterol consumption greater than the median, and coffee use >1 cup/d associated with higher E 2 levels. In a multivariate model, total caffeine use was significantly associated with E 2 levels after adjustment for age, BMI, total calories, current smoking, alcohol, cholesterol consumption, and day of sampling. Early follicular phase E 2 increased from 28.2 pg/mL for women consuming ≤100 mg of caffeine to 45.2 pg/mL for women consuming ≥500 mg of caffeine per day, about a 70% increase.Conclusion(s): Coffee consumption and total caffeine use may increase early follicular phase E 2 levels independent of related habits of alcohol or tobacco use.