A 39-year-old white man was referred to our hospital for evaluation of his jaundice and pruritus. The patient was treated with I for diffuse toxic goiter prior to his referral to our hospital. Clinical examination and laboratory investigations excluded viral hepatitis, autoimmune hepatitis, granulomatous disease, primary biliary disease, extrahepatic biliary obstruction, and heart failure. Liver biopsy showed severe intrahepatic and canalicular cholestasis with minimal inflammatory changes. The patient's jaundice promptly resolved with therapy for hyperthyroidism and thyroid storm as bilirubin levels decreased from 35 mg/dL (normal: 0.5-1.2 mg/dL) to 0.4 mg/dL. Thyrotoxicosis can be an uncommon cause of profound cholestasis. Our case differs from all other reports in the literature because of the severity of the cholestasis and its prompt resolution with treatment for thyrotoxicosis.