Hepatic ischemia reperfusion injury(HIRI) is a clinical condition which may lead to cellular injury and organ dysfunction. The role of nitric oxide(NO) in HIRI is complicated and inconclusive. NO produced by endothelial nitric oxide synthase(e NOS) activation plays a protective role during early HIRI. But e NOS overexpression and the resulting excessive NO bioavailability can aggravate liver injury. NO induced by inducible nitric oxide synthase(i NOS) may have either a protective or a deleterious effect during the early phase of HIRI, but it may protect the liver during late HIRI. Here, we reviewed the latest findings on the role of NO during HIRI:(1) NO exerts a protective effect against HIRI by increasing NO bioavailability, downregulating p53 gene expression, decreasing inflammatory chemokines, reducing ROS via inhibiting the mitochondrial respiratory chain, activating s GCGTP-c GMP signal pathway to reduce liver cell apoptosis, and regulating hepatic immune functions;(2) e NOS protects against HIRI by increasing NO levels, several e NOS/NO signal pathways(such as Akt-e NOS/NO, AMPK-e NOS/NO and HIF-1α-e NOS/NO) participating in the anti-HIRI process, and inhibiting over-expression of e NOS also protects against HIRI; and(3) the inhibition of i NOS prevents HIRI. Thus, the adverse effects of NO should be avoided, but its positive effect in the clinical treatment of diseases associated with HIRI should be recognized. The role of nitric oxide (NO) in HIRI is complicated and inconclusive. NO produced by endothelial nitric oxide synthase (e NOS) activation plays a protective role during early HIRI. But e NOS overexpression and the resulting excessive NO bioavailability can aggravate liver injury. NO induced by inducible nitric oxide synthase (i NOS) may have either a protective or a deleterious effect during the early phase of HIRI, but it Here, we review the latest findings on the role of NO during HIRI: (1) NO exerts a protective effect against HIRI by increasing NO bioavailability, downregulating p53 gene expression, decreasing inflammatory chemokines, reducing ROS via inhibiting the mitochondrial respiratory chain, activating s GCGTP-c GMP signal pathway to reduce liver cell apoptosis, and regulating hepatic immune functions; (2) e NOS prot ects against HIRI by increasing NO levels, several eNOS / NO signal pathways (such as Akt-e NOS / NO, AMPK-e NOS / NO and HIF- 1α-e NOS / NO) participating in the anti-HIRI process, and inhibiting over-expression of e NOS also protects against HIRI; and (3) the inhibition of i NOS prevents HIRI. Thus, the adverse effects of NO should be avoided, but its positive effect in the clinical treatment of diseases associated with HIRI should be recognized.