3,4-diaminopyridine was evaluated for its ability to improve muscle strength, respiratory function and electromyographic compound muscle action potentials in human botulism. In a double blind, placebo controlled study, 3,4-diaminopyridine failed to improve these parameters in a 31-year old patient with severe food-borne type A botulism. The addition of an anti-cholinesterase medication to the 3,4-diaminopyridine did not add any benefit. Lack of clinical improvement from 3,4-diaminopyridine in this patient differed from some reports of benefit in animals experimentally poisoned with type A botulinum toxin.