Although botulinum toxin is thought not to affect the human CNS, previous studies have not examined those behaviors, such as memory, that have been shown to be dependent on central acetylcholine transmission. In eight patients with type A botulism, subjective analysis, bedside memory testing, and formal memory testing with Hebb's verbal sequencing test, Corsi's nonverbal sequencing test, and Buschke's verbal serial list learning test failed to demonstrate impairment in immediate and recent memory. Botulism severe enough to block peripheral nicotinic and muscarinic cholinergic transmission does not block those central cholinergic synapses involved in memory.