The main purpose of this study is to review the function of nitric oxide during sepsis and septic shock. Futhermore, the study reviews the various physiological functions of nitric oxide in the human body, and how these functions can and have been used clinically. Nitric oxide plays an important role during septic shock in contributing to development of hypotension, multiorgan failure and lack of response to pressor therapy. Elevated concentrations of nitric oxide in both circulation and expiratory air have been found in hu-mans and animals during sepsis and septic shock. Further-more, studies show that nictric oxide plays an important role in the immune system. The physiological effect of nitric oxide has been used in various treatments.