Two patients developed cirrhosis of the liver following therapy with perhexiline maleate. Liver failure and polyneuropathy caused death in one patient who had received 300 mg daily for three years. Cirrhosis was an unexpected finding in the other patient whose perhexiline dose was 200 mg daily for five years. Perhexiline should be prescribed cautiously and discontinued if liver function tests become abnormal. Monitoring of blood levels may lead to a reduction of toxicity.