A 41-year-old woman was admitted to our hospital because of scleroderma and combined valvular disease (mitral stenosis, aortic regurgitation, tricuspid regurgitation) associated with massive pericardial effusion. Plasma atrial natriuretic peptide (alpha-hANP) level was 130 pg/ml on admission, and increased temporarily with a decrease of pericardial effusion, without significant of changes of pulmonary capillary wedge pressure, pulmonary arterial pressure, right ventricular pressure nor right atrial pressure. These findings suggest that one of the mechanisms of alpha-hANP secretion, a stretch receptor mechanism, is interfered by the massive pericardial effusion. There was no relationship between atrial pressures and plasma alpha-hANP levels in this case. alpha-hANP concentration in pericardial effusion (486 pg/ml) was four to five folds higher than the plasma alpha-hANP levels.