This is a case report of spontaneous regression of elevated pulmonary vascular resistance after the age of 6 years in a patient with partial endocardial cushion defect. The patient was first evaluated and considered to be highly risky for surgical correction because of obstructive type of pulmonary hypertension and presisting congestive heart failure at the age of 6 years, during which time medical treatment for congestive heart failure and sufferring from respiratory infection were only provided. Finally the patient was reevaluated at the age of 16 years, in January of 1980 when cardiac catheterization was revealed markedly reduced pulmonary vascular resistance and pulmonary hypertension as well. The patient was operated upon with uneventful postoperative recovery. So we report this case with review of the literatures regarding natural history regarding natural history of partial endocardial cushion defect.