We administered measures of object naming and action naming to matched groups of ten patients with Alzheimer's disease (AD) and ten normal control subjects. AD patients were impaired in both object and action naming, with object naming impaired to a significantly greater extent than action naming. This difference remained after controlling for the effects of word frequency. We propose that the pattern of pathological changes in AD impairs both conceptual and lexical retrieval systems for objects but only conceptual systems for actions. The similar patterns of error during the two tasks suggest quantitative rather than qualitative differences in the breakdown of the two abilities.