A 30-year-old female with effusive-constrictive pericarditis was admitted to our hospital because of dyspnea, ascites and edema. On examination, her blood pressure was 118/94 mmHg and her pulse rate was 90 bpm. Physical examination revealed pulsus paradoxus, markedly raised venous pressure and pericardial knock sound. Chest X-ray showed marked cardiomegaly and bilateral pleural effusion. After cardiac catheterization there was elevation of mean right atrial pressure, right ventricular end-diastolic pressure, pulmonary-capillary-wedge pressure, and their pressures during diastole were approximately 30 mmHg. After successful pericardiocentesis, their diastolic pressures still remained at 15 mmHg. Additionally, pressure wave of the right ventricle showed distinct diastolic dip and plateau pattern, and that of the right atrium showed deep x and y descents. The pressure pattern suggested that not only pericardial effusion but also decreased compliance of the pericardium was the main factor contributing to the cardiac diastolic dysfunction. Histological examination of the pericardium showed diffuse lymphocyte infiltration and fibrosis. These findings strongly suggested that there might have been viral infection.