The Computerized Neuropsychological Test Battery (CNTB), a new assessment tool for neuropsychopharmacologic research, is based on a neuropsychological approach. While it is based on tests previously shown to be sensitive to subtle changes in neuropsychological functioning, it differs from currently available tools for measuring central nervous system effects of new compounds. It has sensitivity to a broader range of cognitive functioning and is more comprehensive than other measurements in its sampling of neuropsychological functions, providing wider application to diverse clinical populations. The CNTB is valid, reliable, and has two alternative forms. Use of the computer as an expert system maximizes standardization and ease of CNTB administration and data analysis. Using this assessment tool, three groups of subjects were compared: young and elderly neurologically normal subjects and elderly subjects with the dementia syndrome of Alzheimer's disease (AD). The AD subjects' summary score on the CNTB correlated significantly with the Blessed Information Memory Concentration Test score. The CNTB summary score was significantly higher in young subjects than in neurologically normal elderly subjects, demonstrating sensitivity to the effects of aging. The CNTB summary score also was significantly higher in neurologically normal elderly subjects than in elderly subjects with AD dementia.