To investigate possible differences in tissue exposures to reproductive hormones and to determine hormone-nutrient interrelationships, we studied 10 vegetarian and 10 nonvegetarian premenopausal Seventh-day Adventist women. Over 3 d in each of three consecutive menstrual cycles, we collected diet records, fasting midluteal phase blood, and 24-h urine samples. During each study period, we measured plasma and urinary estrogens, plasma free and protein bound-estradiol-17 beta, the binding capacity of sex-hormone-binding globulin (SHBG), androgens, progesterone, and prolactin levels. The omnivores consumed significantly more protein, total and saturated fatty acids, oleic and linoleic acids, and cholesterol than did the vegetarians. Hormonal status and binding capacity of SHBG were similar in both groups. However, for nonvegetarians, prolactin levels were positively correlated with dietary energy, protein, total and saturated fatty acids, and oleic acid. Further study delineating the effects of specific dietary nutrients on the basal level of prolactin secretion is warranted.