Sperm capacitation and acrosome reaction are essential for fertilization. L-Arginine plays an important role in the physiology of spermatozoa and has been shown to enhance their metabolism and maintain their motility. This study investigated the effect of L-arginine on cryopresreved buffalo sperm capacitation, acrosome reaction and the in vitro fertilizing potentials of the cryopresreved buffalo spermatozoa. Frozen-thawed buffalo spermatozoa have been incubated in TALP medium with different concentrations of L-arginine (5, 10 and 20 mM) and the percentages of capacitated and acrosome reacted spermatozoa have been determined by silver nitrate stain. L-arginine induced both capacitation and acrosome reaction. The optimum concentration that induced capacitation and improved in vitro fertilizing potentials appeared to be 10 mM. The data presented suggested the beneficial effect of L- arginine in cryopresreved buffalo sperm capacitation and acrosome reaction.