Hepatic venous oxygen saturation (ShvO2), parameters of systemic circulation and cytokine (Interleukin 6) (IL-6)) level were measured in 21 patients with thoracic esophageal cancer in order to analyze the mechanism of occurrence of postoperative hyperbilirubinemia (PHB). ShvO2 fell during operation, especially during intrathoracic procedures, and a significant correlation was noted between the total time during which ShvO2 was below 60% and the postoperative peak serum bilirubin level (peak-Bil) (r = 0.595, p = 0.0037). Patients with PHB (group H) had worse systemic circulation and a lower oxygen supply postoperatively than patients without PHB (group N). Body weight and water balance recovered earlier in group N. Postoperatively, numbers of peripheral lymphocytes and platelets changed lower in group H, while CRP and IL-6 changed higher in group H. Furthermore, a significant correlation was noted between the IL-6 level just after operation and peak-Bil (r = 0.669, p = 0.0006). These results suggests PHB results from intraoperative liver hypoxia and poor postoperative systemic circulation. Individual severeness of reactions to the operative stress, excessive or adequate, plays a role in the occurrence of PHB as well.