Vitamin D levels have been linked to various health outcomes including reproductive disorders. The purpose of this study was to explore the association between serum vitamin D level (25-hydroxy-vitamin D, or 25OHD) and semen and hormonal parameters. This is a cross-sectional study that included 170 healthy men recruited for the study of spermatogenesis from the general population. Men completed general and reproductive health questionnaires, and donated blood and semen samples. The main measures were hormonal (total and free testosterone, sex hormone-binding globulin, estradiol, follicle-stimulating hormone and luteinizing hormone) and semen parameters, adjusted (n=147) for age, body mass index (BMI), season, alcohol intake and smoking, in relation to categories of vitamin D levels, determined a priori. The mean age of the study population was 29.0±8.5 years and mean BMI was 24.3±3.2 kg m(-2). The mean 25OHD was 34.1±15.06 ng ml(-1). BMI showed a negative association with 25OHD. Sperm concentration, sperm progressive motility, sperm morphology, and total progressively motile sperm count were lower in men with '25OHD≥50 ng ml(-1)' when compared to men with '20 ng ml(-1)≤25OHD<50 ng ml(-1)'. Total sperm count and total progressive motile sperm count were lower in men with '25OHD<20 ng ml(-1)' when compared to men with '20 ng ml(-1)≤25OHD<50 ng ml(-1)'. The adjusted means of various hormonal parameters did not show statistical difference in the different categories of 25OHD. In conclusion, serum vitamin D levels at high and low levels can be negatively associated with semen parameters.