Median nerve somatosensory evoked potentials(SEP) and electroencephalography(E EG) were recorded in 85 patients with stroke(33 with thalamic hemorrhage, 20 with putaminal hemorrhage and 32 with cerebral infarction) to observe the origin of Nl9 and P23 wave responses in median SEP and the origin of slow waves in EEG as well as to evaluate the prognostic correlation between stroke patients and SEP and EEG findings. Nl9 and P23 were absent in 42 4% of patients with thalamic hemorrhage and 70% with putarninal hemorrhage. There was no case in which only P23 was absent in these two groups. In cerebral infarction, the most frequent finding was that both N19 and P23 were absent. P23 was absent with intact Nl9 in 2 cases with localized cortical infarction. Therefore we suggest that N19 develops in thalamus or thalamocatical pathway and P23 in the parietal cortex. There was no significant difference of EEG findings between thalamic hemorrhage and cerebral infarction. It was unlikely that slow waves on EEG is a specific finding in a localized brain lesion. The prognosis was poor in thalamic hemorrhage and cerebral infarction with loss of both Nl9 and P23 in SEP findings and in cerebral infarction with moderate to severe degree of background abnorrnalities in EEG findings. So that, SEP and EEG findings may be useful for prognostic aspect.