The supplementation of vitamin-B complex reduces lead intoxication. With a view to identify the components of vitamin-B complex responsible for such protection, riboflavin, calcium pentothenate, pyridoxine, nicotinamide, folic acid and cyanocobalamine were investigated for their ability, and their influence on the efficacy of disodium calcium versenate (Na2CaEDTA), to enhance the urinary excretion of lead, mobilize tissue lead and restore lead induced biological alterations in lead intoxicated rats. Folic acid and pyridoxine besides thiamine may be the responsible factors in prophylaxis of lead poisoning by vitamin B complex or in enhancing the antidotal properties of Na2CaEDTA.