Résumé : The effects of somatostatin and vasopressin on blood gases, pulmonary and systemic hemodynamics, and portal pressure assessed by the gradient between occluded and free hepatic vein pressures, were investigated in 18 patients with liver cirrhosis. In the first 10 patients, an iv bolus of 250 microgram somatostatin, followed by an infusion of 125 microgram somatostatin over 30 min, caused a sudden rise in pulmonary and systemic vascular pressures lasting 2 to 5 min and accompanied by bradycardia. There was a slight and transient increase in venous admixture (Qsp/Qt) and alveolar-arterial oxygen tension gradients (P(A-a)O2), and a transient reduction in O2 delivery (O2 del) (-11% of the baseline values) and portal pressures (-14%). In the next 8 patients, vasopressin, 0.4 U/min infused over 30 min, caused a more persistent pulmonary and systemic hypertension and bradycardia, a slight increase in P(A.a)O2 and Qsp/Qt, a reduction in O2 del (-27%) and a decrease in portal pressures (-32%). These effects were marked during the entire vasopressin infusion period. Both somatostatin and vasopressin had vasoconstrictive properties and exerted negative effects on hemodynamics and blood gases. Vasopressin appeared to be a more potent drug than somatostatin.