Three-hour oral glucose tolerance tests were performed on days 5 and 25 of ovulatory menstrual cycles in 26 women. The women were divided into normal (n = 9) and premenstrual syndrome (PMS) (n = 17) categories. Ovulation was confirmed by basal body temperature records and plasma progesterone levels. There were no statistically significant changes in the plasma glucose or insulin levels between the two tests in either group. Except for a higher two-hour plasma insulin concentration on the day 5 test in normal women, no statistically significant carbohydrate differences were noted between the groups. The data suggest that alterations in carbohydrate metabolism are not important in PMS.