A double-blind random administration of 2 mg glypressin intravenously (i.v.) or placebo was given to 20 volunteer patients suffering from liver cirrhosis with portal hypertension and oesophageal varices. Experimental protocol required two basal intravascular oesophageal variceal pressure (IOVP) measurements, before and after bolus i.v. drug injection. The second measurement was taken as reference to determine whether the treatment was effective. Other measurements were taken 1, 3, 5 and 10 min after drug administration. The fall in IOVP at 3, 5 and 10 min in the patients who had been administered glypressin proved statistically significant (p less than 0.01) with mean percentage variations of -22.3%, -24.4% and -27.9%, respectively. In conclusion, the administration of glypressin in portal hypertensive patients brought about a marked reduction in transmural oesophageal variceal pressure in over 70% of the cases. This decrease may prove to be of clinical importance both as a first line therapy and as a possible aid to emergency sclerotherapy in the presence of active variceal bleeding.