Three cases of cholestatic liver disease related to hyperthyroidism are reported. Features indicative of a role of the endocrine disease in the pathogenesis of the cholestatic syndrome were the appearance of liver damage in temporal relation with the clinical onset of thyroid hyperfunction and its disappearance with the amelioration of the hyperthyroidism; the absence of congestive heart failure and of infectious, toxic or obstructive agents of liver damage; the pathological and biochemical findings of intrahepatic cholestasis. Hyperthyroidism can be rarely complicated by a severe cholestatic syndrome that may dominate the clinical presentation and course.