The relationship between stress and certain illnesses is well established. Contemporary studies by stress physiologists suggest that stress may be a factor in a wide variety of illnesses. The original work of Han Selye (the father of physiology) is reviewed in light of more current research. Understanding the mechanisms of physiological responses to stress will set the stage for elucidating the role of adaptogenic herbs in the possible prevention of stress-related illness. In the last portion of the talk, the outcomes from a 3-year trial conducted by MacIntosh and colleagues studying the prevention of colds and flus in a high-stress population are presented.