Weaning from cardiopulmonary bypass is the most important stage during mitral valve surgery, especially in patients with severe pulmonary hypertension. We report two patients with severe pulmonary hypertension who were operated on because of valvular heart disease. To reduce the pulmonary artery pressure, levosimendan was used because of its vasodilatory and cytoprotective effects. All patients tolerated the operation and levosimendan administration. Their postoperative course was uneventful. Levosimendan can be used to treat pulmonary hypertension during operations for heart valve disease. Patients clearly benefit from the vasodilator action of the drug for reducing pulmonary artery pressure.