The incidence and nature of verbal perseveration occuring after cerebrovascular disease were investigated. Out of 59 cases, verbal perseveration was found in 21 of 23 aphasic patients. The perseverative errors were classified into two types;clonic and intentional perseveration. Furthermore, intentional perseveration was divided into two types;immediate and delayed type according to temporal relation of a response to the original stimulus.     Clonic perseveration was found in 5 cases;one in naming and repetition tasks, 5 in series tasks. Intentional perseveration was found in 19 cases ; 17 in naming, 10 in repetition, and 19 in series teasks. There was no correlation between the duration of cerebrovascular disease and perseveration. On CT findings the lesions of frontal lobe, temporal lobe, parietal lobe, thalamus, and basal ganglia were detected. And there were tendencies that the larger the lesion was, the more frequent verbal perseveration was. The hypotheses of mechanism for producing perseveration were reviewed and verbal perseveration was supposed to be related with the disinhibition of memory trace.