The ammonium loading test has been realized in 66 patients, 8 of them without clinical or laboratory data of hepatic disease and 58 diagnosed of hepatic cirrhosis (HC). In 40 patients with HC and 8 patients without liver disease the ammonium was administered by rectum and in the remaining 18 patients with HC it was administrated orally. In each case, non stagnant venous blood was drawn at 0, 30, 45, 60 and 75 minutes after the administration of ammonium and plasmatic levels were measured. The results show that in patients with HC there are no significant differences between rectal and oral administration although the rectal way presented less secondary effects and is better tolerated. The test is discriminatory when comparing patients with HC and patients without liver disease as well as between patients with HC and portal hypertension and those without clinical signs of portal hypertension.