Background : Protein-losing enteropathy (PLE) is well known life-threatening complication of various cardiac diseases. Methods : Retrospective investigation about PLE induced by various cardiac diseases from June, 1986 to June, 2003. Results : Sixteen patients have been diagnosed as PLE of heart origin and treated since June, 1986. Among these patients, 14 patients were induced by Fontan operation (F) and 2 patients by constrictive pericarditis. F had been carried out to 335 patients during that period. Incidence of PLE after F was 3.9% (13/335). Mean age at the F was 5.2 짹 3.4 years and PLE developed at a median 6.4 years (range 0.5 to 16) after F. At the time diagnosed by PLE, mean serum albumin level was 2.18 짹 0.45 g/dL, Fontan pathway mean pressure was 15.1 짹 2.1 mmHg and pulmonary artery mean pressure was 15.5 짹 2.9 mmHg at catheterization (9/14). Five among 14 patients died (35.7%): 2 after Fontan conversion (FC); 1 after biventricular repair; 1 after associated PV stenosis correction; 1 after associated atrioventricular valve replacement. Five corrective operations were done: 4 FC operations; 1 biventricular conversion repair. Among them, 2 patients done FC operation survived, but they have had PLE relapse on partial response with Sildenafil. Five Patients have been treated with heparin and/or prednisolone: 2 good response by heparin; 1 partial response by heparin; 2 partial response by prednisolone. One patient improved by only supportive care including diuretics after 13 months diagnosed by PLE. Two patients have been followed up under the impression of long-standing PLE from constrictive pericarditis. One patient is having normal serum albumin level after pericardiectomy. Conclusion : PLE after F is an unsolved problem with high mortality. Therefore, early diagnosis and vigorous treatment with drug, intervention, and early surgery if necessary, are mandatory. PLE from constrictive pericarditis can be cured by pericardiectomy.