Cerebrotendinous xanthomatosis (CTX) is a lipid storage disease inherited in a autosomal recessive way. CTX is characterised by childhood-onset cataract, adolescent to young adult-onset tendon xanthomas and adult-onset progressive neurological dysfunction (dementia, psychiatric disturbances, pyramidal and/or cerebellar signs and seizures). Xanthomas appear in the second or third decade; they occur on the Achilles tendon, the extensor tendons of the elbow and hand, the patellar tendon and the neck tendons. The biochemical abnormalities that distinguish CTX from other conditions with xanthomas include high plasma and tissue cholestanol concentration, normal-to-low plasma cholesterol concentration and decreased chenodeoxycholic acid. Long-term treatment of individuals with CTX with chenodeoxycholic acid (CDCA) normalises bile acid synthesis, normalises plasma and cerebrospinal fluid concentration of cholestanol, and improves neurophysiological findings. Inhibitors of 3-hydroxy 3-methyl glutaryl coenzyme A reductase alone or in combination with CDCA are also effective in decreasing cholestanol concentration and improving clinical signs; however, they may induce muscle symptoms.