Alterations of the prefrontal cortex (PFC) could contribute to cognitive decline in older adults. We examined the specificity of age-related PFC degeneration and whether cognitive abilities were related to volumetric measurements. Older and younger subjects were tested using a battery of tasks supported by different subregions within the PFC. The cognitive data from older subjects were related to PFC volumetric measurements in order to determine whether cortical morphology was predictive of individual differences in task performance within this age range (72-94 years). Working memory performance best distinguished older from younger subjects. Working memory measures but not other measures were correlated with age in both groups. A larger orbital PFC volume was related to a worse working memory performance and a larger superior PFC volume was related to worse conditional association learning. The volumes of these regions were not related to performance on other tasks. These results suggest that working memory is a sensitive measure of cognitive aging and that regional morphology is associated with specific cognitive abilities in older adults.