Nitric oxide (NO) is animportant biological messenger in the regultlation of tissue homneostasis. It exhibits a wide range of effects during physiolgical and pathophy siological prucesses Typical beneficial ploperties of N0 include the regulation of vascular tone, the protection of cells against apoptosis, the modulation of immune responses, and the killing of microbial patteogens. On the other hand, NO may causese severe vasodilation and myocardial depression during bacterial sepsis or act as a cytotoxic and tissue-damaging molecule in autoimmune diseases Mitogen-activated protein kinase (MAPK) is afamily of serine/threonine protein kinases that in mammalian widely distributed cells. MAPK cascade play pivotal rolesin gene expression, cell prdiferation, differentiation, neuronal survival and pro-grammned cell death under a variety of experimental conditions. MAPKs transduce the signal for the cellular respons to are extracelluar stress-es or stimuli. The rdation between them. however, has never been reviewed Based on Our-researches and 0ther reports in the field, we review their reciprocal regulatury functions.