Information regarding the relationship of menopausal hot flushes to menstrual, reproductive and clinical events were obtained from women participating in a case-control study of breast cancer risk. Naturally menopausal women who reported the occurrence of menopausal hot flushes were compared with those without such complaints in an attempt to identify factors that might predict the occurrence of menopausal symptoms. Two-thirds of the women reported such symptoms. The symptomatic and asymptomatic groups did not differ in body weight, suggesting that extraglandular estrogen production in obese women does not protect against occurrence of menopausal symptoms. Neither past medical nor reproductive history were predictive of the occurrence of hot flushes. Women with hot flushes more commonly reported the occurrence of menstrual cycle variability and of long menstrual cycles during the 5 years before menopause. Since perimenopausal cycle variability probably reflects the irregular maturation of residual ovarian follicles accompanied by elevated gonadotropin concentrations, symptomatic women may have earlier activation of the neuroendocrine mechanism that has been associated with both pulsatile gonadotropin release and the hot flush.