The present study examined the effects of intraventricular administration of the cholinergic neurotoxin ethylcholine aziridinium ion (AF64A) on performance of a radial arm maze task. Male Sprague-Dawley rats were trained to perform a delayed-nonmatch to sample radial arm maze task in which a 1-h delay was imposed between the fourth and fifth arm selections. Following acquisition, animals were injected bilaterally with AF64A (1.5 or 0.75 nmol/side) or artificial cerebrospinal fluid into the lateral cerebral ventricles and allowed 7 days to recover before behavioral testing resumed. Significant dose- and delay-dependent impairments in the radial maze performance were observed in AF64A-treated rats as evidenced by fewer correct choices following the delay and by more errors to complete the task. Long-term testing in this task revealed significant recovery of memory performance. These findings indicate dose-dependent impairments in memory following intraventricular administration of AF64A and spontaneous behavioral recovery following such insult.