There has been an explosive increase in the amount of interesting information about the physiologic and pathophysiologic roles of nitric oxide in cardiovascular, nervous, and immune systems. The possible involvement of the nitric oxide-cyclic guanosine monophosphate pathway in the effects of anesthetic agents has been the focus of many investigators. Relaxations of cerebral and peripheral arterial smooth muscle as well as increases in cerebral and other regional blood flows induced by anesthetic agents are mediated mainly via nitric oxide released from the endothelium and/or the nitrergic nerve and also via prostaglandin I2 or endothelium-derived hyperpolarizing factor. Preconditioning with volatile anesthetics protects against ischemia-reperfusion-induced myocardial dysfunction and cell death or neurotoxicity, possibly through nitric oxide release. Inhibition of nitric oxide synthase decreases the anesthetic requirement. Involvement of nitric oxide in the effects of volatile, intravenous, and local anesthetics differs. This review article includes a summary of information about the sites and mechanisms by which various anesthetic agents interact with the nitric oxide-cyclic guanosine monophosphate system.