The relation of interleukin-6 (IL-6) levels in serum to the postoperative complications was assessed in 50 patients following an extensive hepatectomy. In addition, the postoperative levels of IL-6, tumor necrosis factor-a, and interleukin-1beta in peritoneal exudative fluid were determined in 22 patients. The patients with preoperative biliary obstruction showed a higher incidence of postoperative infection compared to those without (44 vs. 12%, p = 0.043). The postoperative serum IL-6 levels on day 1 were significantly higher in patients with postoperative infection than in those without (p<0.01). Biliary obstruction and intraoperative blood loss contributed to the increase in the serum IL-6 levels in a multiple regression analysis (p = 0.01 and p = 0.044, respectively). Further, the fluid levels of inflammatory cytokines were significantly higher in patients with biliary obstruction than in those without (p<0.05). These results suggest that in patients with biliary obstructions a hyperactive cytokine response occurs after an extensive hepatectomy and results in a high incidence of postoperative infection.