The hormones progesterone and estrogen and, more precisely, their sophisticated interdependent fluctuations over the course of the female human lifespan, have long been known to play a dominant role in the physiological development and homeostasis of the human female. What is only recently coming to light, however, is that the fluctuation of these two hormones also plays a crucial role in neurological and psychological development and function which impacts brain function, cognition, emotional status, sensory processing, appetite, and more. The ability of reproductive hormones to impact psychoneurological processes involves the interplay of several body systems, lending credibility to the view of premenstrual syndrome (PMS) as a disorder founded in real biochemical disturbances. The effects of the menstrual cycle on cognitive, emotional, and sensory function in the female of childbearing age are reviewed. In addition, recent evidence is discussed which confirms the biological basis of PMS as a real disorder of primarily autoimmune origin.