NOS1 and Infertility: The present observational study found no significant differences in the concentrations of PGE2, 6-keto-PGF1α, F2-isoprostane, SOD1, GPX1, NOS1, as well as the ratios: NOS1/SOD1, NOS1/GPX1, GPX1/SOD1, and PGE2/6-keto-PGF1α in seminal plasma from fertile and infertile men, indicating that their discriminative potential is limited for distinguishing fertile from infertile individuals.