Administration of aluminum sulfate in the drinking water of male Sprague-Dawley rats for 30 days resulted in a reduction in the number of days to reach extinction criterion on a passive avoidance task (38% control level). The behavioral deficit was not due to nonspecific effects caused by lower fluid consumption. Partial reversal of the deficit was produced by discontinuing aluminum treatment 2 weeks prior to testing (p < .05). Injection of the aluminum chelator deferoxamine returned the performance of the aluminum-treated animals to control levels in a dose-dependent manner but had no effect on control animals. No differences in open-field activity were evident across groups. These results indicate that the behavioral impairment is a specific, reversible, toxic effect of the aluminum administration.