Echocardiographic features of interventricular septum were studied in four patients with constrictive pericarditis. The systolic motion was normal in one patient and paradoxic in the other three. All four patients had an abrupt anterior motion which was followed by a sudden brisk posterior motion immediately in early diastole, following the diastolic dip of the septum. This motion was coincident with the 'y' trough of the jugular venous pulse. The septal thickening values were within normal range