Depression and anxiety can adversely affect the course of chronic physical illnesses, increasing morbidity and mortality. The literature during the past year is reviewed for gastrointestinal disorders, cancer, pain, heart disease, diabetes, and pulmonary disease. Causes for this relationship are behavioral and biological. Behavioral factors in patients with depressive and anxiety disorders include unhealthy lifestyle choices, disrupted sleep, and poor adherence to medical regimens. Biological mechanisms include increased inflammatory response and disruption of the hypothalamic-pituitary-adrenal axis.