RESUMEN El oxido nitrico es un regulador multifuncional, fundamental para diversos procesos incluyendo la infamacion, vasoregulacion, senalizacion intra e intercelular, apoptosis y carcinogenesis. La falla en la sintesis y/o la perdida de la biodisponibilidad de oxido nitrico es la principal caracteristica de muchas enfermedades. La comprension de los mecanismos subyacentes a los efectos del oxido nitrico a nivel celular y tisular, permitira el desarrollo de nuevas terapias para balancear los efectos del oxido nitrico in vivo . El objetivo de esta revision es mencionar los principales hallazgos en el campo de investigacion relativo a este gas diatomico y su dinamica biologica. Palabras clave: Antioxidante. Especies reactivas del nitrogeno. Especies reactivas del oxigeno. Oxido nitrico. Senalamiento celular. SUMMARY Nitric oxide is a multifunctional regulator, which is central to diverse processes including infammation, vasoregulation, intra-and intercellular signaling, apoptosis, and carcinogenesis. The failure in the synthesis and/or loss of bioavailability of nitric oxide is the main characteristic of many diseases. Understanding the mechanisms underlying the effects of nitric oxide at the cellular and tissue level, will allow the development of new therapies to balance the effects of nitric oxide in vivo. The purpose of this review is to mention the key findings in the feld of research on this diatomic gas and their biological dynamics. Key words: Antioxidant. Radical nitrogen species. Radical oxygen species. Nitric oxide. Cell signalling.