Nitric oxide (NO) has been implicated in the pathogenesis of neurodegenerative disorders such as multiple sclerosis, and Parkinson’s, Alzheimer’s and Huntington’s diseases. Although the production of NO from type I and type II NO synthases appears to be increased in these disorders, this could be a secondary phenomenon, possibly a nonspecific inflammatory response. However, in certain models such as chemically induced Parkinson’s disease and experimental auto immune encephalitis, the pathological charges are blocked by an NO synthase inhibitor, indicating that NO participates in an as yet unknown upstream event leading to pathogenic changes. These promising results warrant further investigation in these areas and innovative treatments for neurodegenerative disorders are anticipated.