Disulfiram was administered for either 4 or 10 days to young, otherwise nonmedicated normal volunteers. In all subjects disulfiram prolonged the antipyrine half‐life and reduced urinary vanilmandelic acid (VMA) excretion; after disulfiram was discontinued, antipyrine half‐lives and VMA excretion returned toward normal. These results suggest the possibility of toxicity from dmg accumulation when certain other therapeutic agents are administered simultaneously with disulfiram. Such toxicity from diphenylhydantoin or warfarin has been reported in isolated case studies of patients receiving disulfiram. Since disulfiram administration alters catecholamine metabolism, patients receiving disulfiram should not be expected to exhibit normal parameters of catecholamine turnover. Effects of disulfiram on antipyrine and catecholamine metabolism reveal that disulfiram is not a selective inhibitor of aldehyde dehydrogenase but exerts several discrete inhibitory actions which should be recognized during its administration.