Mechanical ventilation is a valuable therapeutic option in left ventricular failure because of its effect on ventricular load. However, weaning cardiac patients form mechanical ventilation may result in severe pulmonary oedema, especially if it is not properly prepared. Some of the factors which contribute to pulmonary oedema are: 1) increased venous return due to the inversion ot the regime of inthrathoracic pressures and the release of catecholamines commonly observed during weaning, 2) reduction of left ventricular compliance due to myocardial ischemia, compression of the cardiac chambers by the lungs, ventricular interdependence in some cases and left ventricular dilatation in others, 3) increased left ventricular afterload due to negative intrathoracic pressures and increased systolic blood pressure. Of all the causes of unsuccessful weaning, left ventricular dysfunction should be carefully considered because its treatment alone may enable the patients to be taken off the ventilator. The authors report six cases of pulmonary oedema in coronary patients after discontinuing mechanical ventilation. The administration I.V. enoximone, a phosphodiesterase inhibitor, prevented acute left ventricular dysfunction in 5 of the 6 cases and enabled successful and definitive weaning from mechanical ventilation.