It is known that the administration of a cholinergic receptor blocker impairs the rat's performance on the place learning version of the Morris water task. We confirm this finding but in addition report that animals receiving the cholinergic antagonist, scopolamine hydrobromide, are significantly impaired on the cued platform version of the Morris water task. This latter result, however, is dependent on both the age of the subject and the training context. Weanling animals were more impaired on the cued platform task than were adult animals, and the magnitude of the impairment was much larger when animals were trained in a pool with a gray interior wall than when the pool wall was white. Our findings suggest that the influence of cholinergic systems on performance in the Morris task extend beyond their contribution to place learning and memory processes. We suggest that functional central cholinergic systems also contribute to the processes that enable the animal to inhibit behaviors that are incompatible with the requirements of the task.