A positive dose-dependent effect of carnosine (beta-alanyl-L-histidine) on the lifespan of male Drosophila melanogaster flies was shown. The mean lifespan of male flies receiving 200 mg/liter carnosine approached that of females. At the same time carnosine had no effect on the lifespan of female flies. This positive effect of carnosine probably reflects its protective action against age-related accumulation of free radicals and did not depend on carnosine metabolism in the body. Addition of 200 mg/liter histidine and beta-alanine (separately or in combination) had no effect on the mean lifespan of flies.