Distinguishing constrictive pericarditis from restrictive cardiomyopathy, usually due to amyloidosis, is a relatively frequent and difficult diagnostic problem. This report describes, for the first time, a patient with constrictive pericarditis caused by direct, extensive infiltration of the pericardium by amyloid, with only minimal amyloid in the myocardium, and a normal heart weight of 320 g. This patient demonstrates that amyloid may be predominantly deposited in the pericardium and actually cause constrictive pericarditis, as well as simulate its hemodynamic presentation by myocardial deposition. Given a clinical and hemodynamic presentation compatible with either constrictive or restrictive disease, an endomyocardial biopsy or other biopsy revealing amyloidosis does not necessarily rule out pericardial constriction that may be due to amyloid infiltration. The relationship between constrictive pericarditis, seen in this patient, and the other more common manifestations of amyloid heart disease, and the hemodynamic profiles of amyloid cardiomyopathy and constrictive pericarditis are reviewed.