The areas of cerebellar damage most commonly associated with dysarthria were sought by reviewing the clinical, radiographic, surgical, and autopsy findings in patients with nondegenerative cerebellar disease. Case histories on 162 patients with focal cerebellar lesions were reviewed. All but 15 of the patients underwent surgery, and 28 had autopsies. Thirty-one of the 122 patients with adequate descriptions of speech had dysarthria. Twenty-two of these 31 dysarthric patients had exclusively or predominantly left cerebellar hemisphere disease; 7 had right hemisphere disease; and 2 had vermal disease. Only 19 of 41 patients with exclusively or predominantly left hemisphere disease had had normal speech before surgery. Dysarthria developed in isolated cases following cerebellar resections extending into the paravermal segments of the left hemisphere. There was no correlation between the extent of vermal damage and development of abnormal speech. Cerebellar speech function was most commonly affected with damage to the superior portion of the left cerebellar hemisphere.