The concentration of total bile acids in the serum was measured in thirty-three patients before and after esophageal transection for esophageal varices, in an attempt to determine the influence of this surgery on the naturally developed portasystemic shunt and also the liver function relating to the bile acid metabolism. The levels of fasting total bile acids in the serum were decreased on the first postoperative day, but gradually increased up to the preoperative levels by the twenty-first postoperative day. The maximum value of total bile acids, as determined in ursodeoxycholic acid tolerance tests, was decreased after the esophageal transection (p less than 0.01). The average of the maximum total bile acids in UDCA tolerance tests was 79.5 microM in the preoperative stage, and 61.0 microM in the postoperative stage. This finding suggested that esophageal transection abolished the portasystemic collaterals and contributed to an increase in efficient hepatic blood flow, which led to the improvement of liver function.