Portal vein (PV) stenosis may contribute to operative death after extended hepatectomy combined with PV reconstruction leading to impairment of the intestinal mucosal barrier. This study was designed to investigate whether rats undergoing such surgery developed endogenous endotoxemia and increased intestinal permeability. The effect of a prostaglandin I2 (PGI2) analogue on mucosal barrier function was also studied. The rats were divided into the following five groups: sham operation, massive hepatectomy (Ht), PV stenosis (PS), combined Ht and PS (Ht+PS), and Ht+PS with subcutaneous injection of PGI2 preoperatively (PG). The 10-day survival rate, portal endotoxin level and intestinal permeability (two-sugar test) were evaluated in each group. The Ht+PS group showed a significant increase in both the portal endotoxin level and intestinal permeability (p < 0.05) and a significant worse 10-day survival (p < 0.01) than the other four groups. PGI2 pretreatment did not influence splanchnic blood flow, but decreased the endotoxin level and reduced intestinal permeability. In conclusion, the synergistic effect of massive hepatectomy and PV stenosis induced an increased intestinal permeability and consequently endotoxemia. PGI2 pretreatment significantly improved both intestinal barrier function and survival.