According to the result of the visual naming task of 100 realistic pictures, 51 cases were selected from 450 cases with various types of aphasia and divided into two groups, namely, meaningless speech group and paraphasic group. Subsequently, on the basis of the quantitative and qualitative valuation of the spontaneous speech and the naming task, the two groups were subdivided with meaningless speech group being recurring utterance (RU group), undifferentiated jargon (UJ group), asemantic jargon (AJ group) and paraphasic group being literal paraphasia (LP group), verbal paraphasia (VP group). Using a microcomputer, the locus and extent of the lesions, as demonstrated by computed tomography for each group were superimposed onto standardized matrices. The relationship between the focus and the extent of the lesions and the various groups was investigated. RU group (n = 8): The size of the lesions of this group was very large and almost all patients had extensive lesions involving frontal-temporal-parietal lobes. There was marked concentration of the lesions in the area of the insula, lenticular nucleus and the deep structures of the frontal lobe. UJ group (n = 9): In general, the size of the lesions was large and highly involved lesions were located in the lenticular nucleus and operculum as well as the superior and middle temporal gyri and the supramarginal gyrus. Because of the large variability in lesion patterns, it has proved to have little localizing value. AJ group (n = 11): The size of the lesions was significantly smaller than any other group. At least 80% of the patients had the superior temporal lesions involving Wernick's area and subcortical lesions of the supramarginal gyrus. LP group (n = 8): The lesions were relatively large in size. While there was some concentration of the lesions in the area of the lenticular nucleus, posterior parts of the insula and anterior temporal gyrus, it was difficult to localize in a definite region. VP group (n = 15): The lesions of this group were a little smaller and located slightly deeper than those of the LP group. The finding has proved to have little localizing value.