This study examined blood pressure and heart rate responses to a mental arithmetic task in a sample of 16 regularly menstruating women during the follicular (postmenstmal) and luteal (premenstrual) phases of their menstrual cycles. Self-reports of physical and psychological symptoms (mood) were obtained prior to testing. A control group of men was matched to the women with regard to age and yoked to the women's cycle phases. Both women and men were told the study involved "phases of the moon" in order to eliminate subjects' awareness of participating in a biological cycle study. Consistent with prior studies that have eliminated women's awareness of taking part in a study on menstrual phases, no phase differences in mood were evident nor did the women's mood ratings differ from those of men's. In addition, there were no phase differences in blood pressure and heart rate reactivity. These findings suggest that hormonal variations characteristic of the luteal and follicular phases do not assert an influence on common assessments of cardiovascular stress reactivity.