Calcium is essential for functioning of different systems including male reproduction. However, it has also been reported as chemo-castrative agent. The study has been undertaken to elucidate the effect of excessive dietary calcium on male reproductive system in animals with possible action. Adult male healthy rats fed CaCl2 at different doses (0.5, 1.0 and 1.5 g%) in diet for 13 and 26 days to investigate reproductive parameters as well as the markers of oxidative stress. Significant alteration was found (P<0.05) in testicular and accessory sex organs weight, epididymal sperm count, testicular steroidogenic enzyme (Δ5 3β-HSD and 17β-HSD) activities, serum testosterone, LH, FSH, LPO, activities of antioxidant enzymes, testicular histoarchitecture along with adrenal Δ5 3β-HSD activity with corticosterone level in dose- and time-dependent manner. Overall observations suggest that excessive dietary calcium enhances the generation of freeradicals resulting in structural and functional disruption of male reproduction. © Springer Science+Business Media, LLC. 2011.