Increasing insight into the mechanisms of perioperative physiologic responses and the resultant effects on patient outcome suggests that some responses may be detrimental to long-term recovery. Thus, initial belief in the adaptive "wisdom" of the body has been supplanted by the concept that a "stress-free" perioperative period may minimize detrimental physiologic responses and resultant morbidity. The perioperative use of neuraxial- or regional anesthesia and analgesia have profound inhibitory effects on the body's response to surgery compared to the same operation performed during general anesthesia alone. Increasing evidence has emerged suggesting that such afferent nociceptive blockade may improve a variety of postoperative morbidity parameters and improve surgical outcome. We review the clinical evidence from studies examining the effects of regional anesthesia and analgesia on postoperative morbidity in specific physiologic systems.