Test scores from a comprehensive neuropsychological battery administered to 1602 subjects consisting of 1347 subjects with probable Alzheimer's disease (AD), 100 subjects with questionable dementia (QD) and 155 non-demented elderly control subjects were cross-sectionally analyzed. Subjects with probable AD were categorized as mild (n = 244), moderate (n = 480), severe (n = 376), and very severe (n = 247) according to modified mini mental status exam (mMMSE) scores. Mean scores on individual neuropsychological tests are provided for each group of subjects. Stratified random sampling was performed to select a sample of mild AD subjects who were matched in age and education to non-demented elderly controls, and analyses focused on the performance of QD subjects and mild AD subjects, whose scores were compared to those of the elderly control subjects. Selected scores were organized by cognitive domain and logistic regressions were used to determine the domains and individual tests within each that were most predictive of group status. Results suggested a profile of scores associated with QD and mild AD including impaired recall of verbal information for both groups. Areas of lower functioning in QD subjects as compared to elderly controls included category fluency and visuospatial ability. (JINS, 2003, 9, 720–732.)