IN 1937, one of the authors (L.V.B.) published the first case of what has since come to be known as cerebrotendinous xanthomatosis (CTX).1Subsequent clinical reports2-8have confirmed the fact that we are dealing with a distinct clinical entity consisting of juvenile cataracts, tendinous xanthomas, and dull normal intelligence, often associated with a positive family history. This disease has a deteriorating course characterized by cerebellar ataxia after puberty, systemic spinal cord involvement and, finally, a pseudobulbar phase leading to death. Despite this characteristic picture, some reports have included cases of cerebral arteriosclerosis,9-12even though these patients did not have any cataracts. A few cases of this disorder have had hypercholesterolemia; however, in general, the serum cholesterol has been normal. Recently, biochemical examination of the brain has revealed cholestanol storage.13 The present report gives a complete clinical, pathological, and biochemical study of a relative of the