Fifteen women prospectively diagnosed with PMS and 15 non-PMS women were each tested twice for cardiovascular stress reactivity and behavioral performance, once during the follicular phase and once during the luteal phase of their cycle. Although blood pressure and heart rate responses to stress did not differ across the menstrual cycle in either group of women, for the non-PMS women, differences in hemodynamic responses were observed across the 2 phases. The luteal phase was associated with greater stroke volume responses and lesser vascular tone. For the PMS women, none of their cardiovascular measures differed across their cycle. Instead, these women showed significantly attenuated blood pressure and heart rate responses compared with non-PMS women, irrespective of cycle phase.