Constrictive pericarditis following an open cardiac surgery for congenital heart disease is very rarely encountered in children. We report a case of constrictive pericarditis, diagnosed at 22 months after surgical closure of an atrial septal defect, in a 14-year-old boy who presented postpericardiotomy syndrome. Cardiac catheterization revealed uniformity of elevated diastolic pressures in all chambers, prominent x and y descents in the right atrial pressure tracing, and typical "dip and plateau" contour of ventricular end-diastolic pressures. Pericardiectomy improved the hemodynamic status of the patient. He remains symptom-free during the follow-up period of 12 months.