Computed tomography (CT) was abnormal in 75 percent of 33 patients with pure motor hemiparesis (PMH). In 13 cases, lesions were detected in the capsular region; 10 were consistent with infarction, and 3 were of increased density consistent with hemorrhage. Seven had other vascular disorders, and four had nonvascular conditions. Of 20 patients with PMH with normal electroencephalogram (EEG), isotope scan, and cerebrospinal fluid, 11 had CT evidence of a lesion in the internal capsule-corona radiata region. In patients with PMH with normal CT, recovery was more complete and rapid than in those with CT evidence of a vascular lesion. In 5 cases, CT showed a capsular lesion, although the patients had never had any neurologic deficit.