Age-related cognitive deficits in both humans and experimental animals appear to relate to dysfunction of basal forebrain cholinergic neuron systems. The present study assessed spatial learning performance in a water maze task as a function of choline acetyltransferase and high-affinity choline uptake specific activity (the two phenotypic markers for cholinergic neurons) in frontal cortex, hippocampus and striatum of aged male Fischer-344 rats. We observed that increased hippocampal choline acetyltransferase activity was related to better performance on the water maze task, and that, of the individual measures, hippocampal choline acetyltransferase activity was the best predictor of behavioral performance in the spatial learning task.