We evaluated the early postoperative response of several cytokines (IL-2, IL-4, IL-6, IL-10, TNF-alpha, IFN-gamma) prior to liver transplantation (T(0)) as well as 1, 6, and 12 hours and 1, 2, 3, 5, and 7 days afterward. Cytokine concentrations were correlated with serum levels of bilirubin as a predictor of postoperative complications. Cytokine levels were determined in plasma samples from 16 liver transplant recipients (13 men, 3 women) aged 43 to 61 years. IL-6 and IL-10 reached their maximum concentrations 1 hour after transplantation. Each increase in IL-6 correlated to a rise in IL-10. IL-2, IL-4, TNF-alpha, and IFN-gamma had a particular time-course for each patient studied. Bilirubin fell to almost normal values but not in cases of postoperative complications, where IL-6 showed values four times higher compared to those of liver transplant recipients who did not show postoperative complications. IL-6 and IL-10 plasma concentrations and serum bilirubin level might be useful as a predictive factor of postoperative complications in liver transplant recipients.