Objective:To evaluate correlation between the levels of vitamin D and male infertility as well as to determine the efficacy of vitamin D in improving the male fertility by up-regulating the levels of testosterone and spermatogenesis.Methods: In the present study, 130 male patients (aged 25-70 years) having fertility defects were screened and 145 healthy individuals were taken as control. All human subjects were screened for 4-hydroxynonenal, isoprostane-F2α, 8-hydroxy-2′-deoxyguanosine, vitamin D, luteinizing hormone, follicle stimulating hormone, testosterones, malondialdehyde, superoxide dismutase, catalase, glutathione peroxidase, and nitric oxide.Results: The screening analysis revealed that the levels of luteinizing hormone, follicle stimulating hormone, and testosterone were lower in male infertile subjects compared to healthy subjects. Similarly, the levels of vitamin D [(17.17 ± 2.30) ng/mL] and calcium[(6.29 ± 0.31) mg/dL] were significantly lower in infertile groups compared to the normal healthy groups. Moreover, the study revealed that the levels of superoxide dismutase, catalase, and glutathione peroxidase were significantly higher in healthy subjects compared to the infertile subjects.Conclusions:Vitamin D exhibits strong relevance to male fertility by maintaining the levels of sex hormones (luteinizing hormone, follicle stimulating hormone, and testosterone), up-regulating the antioxidant defense (superoxide dismutase, catalase, and glutathione peroxidase), and down-regulating the oxidative stress (malondialdehyde, nitric oxide, and inducible nitric oxide synthase species).