An adult patient with chronic idiopathic intestinal pseudo-obstruction maintained on home parenteral nutrition for 6 consecutive years died from cardiomyopathy and ventricular fibrillation. Postmortem examination of the heart revealed widespread myocytolysis and replacement fibrosis similar to that seen in the selenium deficient cardiomyopathy in China (Keshan disease) and animal models. Selenium deficiency in this patient was documented with extremely low concentrations of selenium and decreased activity of the selenoprotein, glutathione peroxidase, in blood, heart, liver, and skeletal muscle. Reports of selenium deficient diets causing myocardial damage in humans and animals and the findings in our patient strongly suggest that his fatal cardiomyopathy was caused by selenium deficiency.