L-arginine plays a key role in modulating host defenses and cellular immunity. It also actively participates in sperm formation A deficiency in L-arginine causes derangement of sperm metabolism leading to decrease in motility and loss of spermatogenesis . Administration of L-arginine to oligospermic and asthenospermic patients results in an improvement in both the sperm count and motility without any side effect. L-arginine plays an important role in stimulating sperm motility in humans, rabbits, and goats under in vitro conditions . L-arginine enhances the rate of glycolysis, resulting in higher rates of ATP and lactate generation in spermatozoa . The influence of arginine in reversing impairment caused by glycolytic inhibitors (potential contraceptives) has also been studied. The reversal effect of arginine involves an eight-fold higher metabolic activity compared to inhibited cells. Structurally related amino acids such as nitro-arginine, homo-arginine, lysine, and ornithine are ineffective .