The purpose of this study was to determine whether arterial spin labelling (ASL) at 3-T MR imaging can be used to discriminate individuals with Alzheimer's disease (AD) from cognitively normal subjects. Twenty AD patients and 23 cognitively normal control subjects were studied using ASL on a 3-T MR imager. Absolute regional cerebral blood flow (rCBF) maps were calculated. In addition, normalized rCBF maps were obtained using CBF in the sensorimotor cortex for normalization. A voxel-wise comparison of these rCBF maps between the AD and control groups was performed using the two-sample t test. Individuals with AD were discriminated from control subjects based on mean rCBF values within a region-of-interest defined by the t test, and the discriminating performance was evaluated by the receiver operating characteristic (ROC) analysis. Comparisons of both absolute and normalized rCBF maps revealed areas of significant hypoperfusion caused by the effects of AD in the bilateral precunei and posterior cingulate gyri. ROC analyses resulted in area under the curve (AUC) values of 0.861 to 0.877 for absolute and 0.910 to 0.932 for normalized rCBF. Our results suggest that ASL at 3-T MR imaging can be used to help discriminate individuals with AD from normal subjects.