Signal detection measures olfactory sensitivity (d') and measures of blood pressure, heart rate, body temperature, nasal airflow, and respiration rate were repeatedly established within approximately 2.5-hr test sessions held every other day across 17 menstrual cycles of women not taking oral contraceptives, 6 menstrual cycles of women taking oral contraceptives, and 6 equivalent time periods of three men. In addition, radioimmunoassay-determined serum levels of luteinizing hormone, follicle stimulating hormone, estrone, estradiol, progesterone, and testosterone, as well as responses to the Moos Menstrual Distress Questionnaire (MDQ), were established daily or bidaily throughout the study periods. Peaks in olfactory sensitivity were noted during the second half of menses, midcycle, and midluteally in women taking and in women not taking oral contraceptives. The lack of correlation between the fluctuations in d' and the circulating hormone levels in the group using oral contraceptives suggests factors other than gonadal hormones were responsible for these changes. Significant fluctuations were also noted across the cycle phases of the normally cycling women for all the hormones examined, as well as for body temperature, nasal airflow, and the MDZ Water Retention and Pain Scales. In the oral contraceptive group, very small but statistically significant changes were observed across the cycle in body temperature and in circulating levels of luteinizing hormone and estrone. Interrelations between a number of the variables were noted both within and across the test periods in all three subject groups. The results are discussed in relation to fluctuations reported in a number of sensory systems during the menstrual cycle.