Greater fear or distress prior to surgery is associated with a slower and more complicated postoperative recovery. Although anxiety presumably interferes with recuperation through both behavioral and physiological mechanisms, the pathways have been unclear. Recent work in psychoneuroimmunology (PNI) has demonstrated that stress delays wound healing. In addition, a second line of research has illustrated the adverse effects of pain on endocrine and immune function. A biobehavioral model is described that is based on these and other data; it suggests a number of routes through which psychological and behavioral responses can influence surgery and postsurgical outcomes. Clinical and research implications are highlighted.