Background:  Vitamin-D is one important steroid hormone in the body, which is obtained from direct sunlight and food or supplements. Objective: The current study aimed to evaluate the relationship between Vitamin-D levels and semen parameters among infertile men in Najaf Governorate. Patients and method: The study included sixty infertile men who presented to the Infertility Unit, Saad Medical City during the period from January 2020 to September 2020. The results were compared with the results of thirty healthy men as a control group. The level of Vitamin-D in the blood was detected using a French-origin Fujifilm machine, semen analysis, and sperm counting by using a Microcell counting chamber. Sperm morphology was evaluated by the Diff-Quick kit. Results: The results demonstrated that infertile men had average age of 34 ± 0.50 years and their mean body mass index (BMI) was 60.60 ± 5.06 kg/m². The results showed that the level of vitamin-D in the body recorded a significant decrease (P-value < 0.0001) in infertile men (12.55 ± 0.02) as compared to fertile men (43.16 ± 0.005). Conclusion: This study proved the positive relationship between the level of Vitamin-D and the levels of semen parameters, which can insure for the possibility of relying on the level of Vitamin-D in determining the cause of male infertility.