The antiosidant activity of carnosine and related compounds such as anserine, homo-carnosine, histidine, and $eta$-alanine which are found in most mammalian tissues, was investigated using hypochlorite (HOCl)-induced oxidant systems. Carnosine and related compounds were protective against HOCl-induced ascorbic acid oxidation, as determined by UV absorbance at 265nm. L-histidine was the most effective among them. The inhibitory effect of these compounds was strongly associated with a decrease in HOCl. It was also found that carnosine and related compounds significantly protected against the HOCl-mediated erythrocyte damage, as determined by hemoglobin release and gemolysis (p<0.05). Carnosine and anserine also inhibited of $alpha$-antiprotease($alpha$-AP) by HOCl, thereby inactivating porcine elastase. The inhibitory effect of carnosine on inactivation of $alpha$-AP by HOCl depended on the concentration of carnosine and on the time preincubated with HOCl. Homocarnosine, histidine, and $eta$-alanine did not inhibit the reaction. These results indicate that carnosine and related compounds can neutralize or scavenge HOCl. Thus, these compounds may play an important role in protecting against HOCl-mediated damage of biomolecules in vivo.