OBJECTIVE To study the relationship between relative regional cerebral blood flow (rCBF) and performance on a variety of neuropsychological tests in a group of subjects with Alzheimer's disease. METHODS Analysis of the relationship between relative rCBF and neuropsychological performance using stepwise multiple regressions and Pearson Product-Moment Correlation coefficients. METHODS University dementia clinic and research laboratory. METHODS Twelve mildly demented patients with Alzheimer's disease (Mini-Mental State examination [MMSE] scores, 24 to 29; age, 56 to 78 years); 38 moderately demented patients with Alzheimer's disease (MMSE scores, 0 to 23; age, 59 to 86 years); and eight normal control subjects (MMSE scores, 27 to 30; age, 61 to 79 years). METHODS Single photon emission computed tomography and the blood flow tracer N-isopropyl-p-iodoamphetamine iodine 123 were used to measure relative rCBF. Cognitive performance was assessed by grouping neuropsychological tests into clusters reflecting frontal lobe abilities, perseveration, memory, and visuoconstructive abilities. RESULTS While MMSE score was a significant (P < .05) predictor of visuoconstruction, frontal lobe, and memory cluster scores, relative rCBF was a weaker predictor of neuropsychological performance, with only right orbitofrontal relative rCBF emerging as a significant (P < .05) predictor of the frontal cluster score and right parietal relative rCBF as a significant (P < .05) predictor of the visuoconstruction cluster score. CONCLUSIONS These results support our a priori grouping of neuropsychological tests into frontal and visuoconstruction clusters and suggest that these two clusters are good measures of frontal and parietal lobe function, respectively.