To provide an overview of current knowledge, this article reviews experimental and clinical data from investigations examining effects of regional anesthesia on perioperative morbidity in specific physiologic systems. The issues of morbidity and mortality following general and regional anesthesia are addressed, as are the development of perioperative thromboembolism and blood loss, which are known to be increased during general anesthesia. Finally, the effects of regional anesthesia on the vascular system, the perioperative stress response, and the pulmonary function are discussed.