Experimental animal studies have suggested that certain vasodilators could minimize the adverse cardiovascular effects of vasopressin. We investigated the hemodynamic effects of isosorbide dinitrate, alone and in combination with vasopressin, in patients with liver cirrhosis. In 10 patients, isosorbide dinitrate, 5 mg sublingually, reduced portal pressure by 21% as assessed by the gradient between wedged and free hepatic venous pressure, but also decreased mean arterial pressure (MAP) by 20%, pulmonary artery wedge pressure (WP) by 50%, and oxygen delivery (DO2) by 13%. In 6 other patients, isosorbide dinitrate, 5 mg sublingually, combined with vasopressin, 0.4 U/min iv, reduced portal pressure by 37%, increased MAP by 13%, and mean pulmonary artery pressure (MPAP) by 70%, and decreased DO2 by 32%. Thus, isosorbide dinitrate reduces effectively portal hypertension in patients with liver cirrhosis, but also decreases DO2 to the tissues as a consequence of a fall in cardiac output due to decreased preload. At the dosage used in this study, isosorbide dinitrate does not prevent the adverse hemodynamic effects of vasopressin.