Behavioral ratings on several affective scales (non-erotic/erotic, unpleasant/ pleasant, simple/complex and low arousal/high arousal), and electrophysiological responses (event-related brain potentials) to emotional pictures, were collected from 30 female subjects, at different phases of their menstrual cycle. The pictures belonged to 5 emotional categories, whose content was babies, dermatological cases, ordinary people, male models and female models. The subjects were grouped into hormone defined phases, according to their expected levels of androgens, estrogen or progesterone. The data were analyzed to determine if emotional or cognitive processing was sensitive to the reproductive status, as indicated by menstrual phase. Only one component of event-related potentials, the P3 component, varied with menstrual phase. Baby and male model pictures elicited larger P3 waves when progesterone level was high. High progesterone was also associated with a decrease in complexity and eroticism to all picture categories. An increase in the pleasantness of all categories was evident when estrogen levels were high. The results are interpreted as support for a general proximal design, whereby emotional and cognitive processes are adaptively regulated by reproductive status.