The authors reports the results of 171 cases of portal systemic by pass operations out of a total of 200 cases operated on between 1968 and 1974. These 171 patients all presented with a syndrome of portal hypertension with oesophageal varices and all had previously bled. Their age lay in 70 p. cent of cases between 40 and 60 years and the cause of hypertension was in 96 p. cent of cases an intra-hepatic block. 41 p. cent were included in the risk group A according to Child's classification, 51 p. cent in Group B and 8 p. cent in Group C. The routine operation was side-to-side portacaval anastomosis (75 p. cent). The operative mortality was 5.2 p. cent in all with 1 p. cent in cases with risk A, and 15 p. cent in cases with risk C. The fall in portal pressure was on average 15 cm of water, i.e. 41 p. cent of the initial pressure. The overall survival after 5 years was 65 p. cent, 70 p. cent for risk A and 26 p. cent for risk C. In 69 p. cent of cases the cause of death was liver failure. Encephalopathy, studied in 76 patients over an average period of 3 years, occurred in 39 p. cent of cases, and in 13 p. cent of the latter it was serious. In the 12 p. cent of survivors, we noted recurrent hemorrhage, but in only 2.5 p cent of cases did the bleeding definitely come from oesophageal varices. In the light of these results, the authors judge positively the surgical treatment of portal hypertension.