Olfactory sensitivity to Exaltolide was assessed with a signal detection procedure. In four women tested through five complete menstrual cycles, significant shifts in sensitivity were noted in three cycles for which rectal temperature changes indicated ovulation, but in only one of two anovulatory cycles. In addition, one pregnant woman showed improvement as the number of weeks prior to parturition decreased and one hypogonadal and apparently anosmic woman became increasingly sensitive to the Exaltolide odor while undergoing estrogen therapy. These results confirm and extend previous reports that olfactory sensitivity varies according to hormonal status.