According to the recent data, nitric oxide (NO) is a chemical messenger that mediates functions such as vasodilation and neurotransmission, it also possesses antimicrobial and antitumoral activities. Nitric oxide has been implicated in neurotoxicity associated with stroke and neurodegenerative diseases, neural regulation of smooth muscle, including peristalsis, and penile erection. We searched for full-text English publications in Pubmed and SNPedia databases using keywords and combined word searches (nitric oxide, single nucleotide variants, single nucleotide polymorphisms, genes) over the past 15 years. In addition, earlier publications of historical interest were included in the review. In our review, we have sum up all NOS1, NOS2, NOS3, and NOS1AP single nucleotide variants (SNVs) involved in the development of mental disorders and neurological diseases/conditions. The results of studies we have discussed in this review are contradictory, that might be due to different designs of the studies, small sample sizes in some of them, as well as different social and geographical characteristics. However, the contribution of genetic and environmental factors has been understudied, that makes this issue increasing for researchers as the understanding of these mechanisms can support a search for new approaches to pathogenetic and disease-modifying treatment.