A case is described of a young woman who first showed manifestations of schizophrenia in childhood. At the age of 13 years evidence was present of what was authoritatively diagnosed as a progressive degenerative cerebellar syndrome and her condition continued to deteriorate. Improvement commenced shortly after the institution of megavitamin therapy, notably nicotinic acid 3 grams daily. Her subsequent educational progress was satisfactory and her social rehabilitation is now complete. No medication other than nicotinic acid is required.