Presence or absence of aphasic syndrome and its duration were related to the volume of hematoma calculated from CT in 27 consecutive non-surgical cases with left putaminal hemorrhage. In the present study, patients classified into three groups regardless of the types of aphasia; i.e. non-aphasics, transient aphasics and persistent aphasics. Transient aphasics were arbitrarily defined as cases who had presented with more or less evident aphasic syndrome in the acute stage, but almost completely recovered in the chronic stage. Volume of hematoma in non-aphasic patients ranged from 2 to 17 ml, with a mean of 7.7 ml and those in transient cases were from 11 to 23ml with a mean of 17ml. All but one case with persistent aphasia showed the hematoma volume larger than 25ml. This exceptional case was a 83 year-old female who showed marked cortical atrophy on CT. Consequently, the presence of aphasia and its persistence seem to be largely dependent on the size of hematoma in patients with left putaminal hemorrhage. Persistent aphasia may be caused by organic damage of subcortical white matter, when the volume of hematoma exceeds around 25ml.