We assessed the regional cerebral blood flow (rCBF) in 8 patients with subcortical aphasia and 8 patients with subcortical infarction without aphasia using the N-isopropyl-P-[123I]-iodoamphetamine autoradiography (123I-IMP ARG) method. In this study, we evaluated vermis to left cortex ratio of CBF. In cases of Broca's aphasia (N = 2), CBF was lower in the posterior frontal regions including Broca's area, and more hypoperfused in the posterior frontal and in the posterior temporal regions, including Wernicke's area of total aphasia (N = 2). But, it was not significantly hypoperfused in those regions in the cases of Wernicke's (N = 2) and amnestic aphasia (N = 2). In the subcortical aphasia, global CBF in the left cerebral cortex was lower than that in the right cerebral cortex. However, in the subcortical infarction group without aphasia there was no difference between CBF in the left cerebral cortex and the right cerebral cortex. We conclude that hypoperfusion in the left cerebral cortex was greater than that in the right cerebral cortex and it was probably due to dysfunction of the left cerebral cortex when subcortical infarction occurred with aphasia. Though some types of aphasia were not relative to the dysfunction of the left cerebral cortex.