Abstract Background: The use of cardiopulmonary bypass (CPB) in open heart surgery is frequentl associated with organ dysfunction. We evaluated the patterns of serum bilirubin, enzymes level and early clinical outcomes of postoperative liver dysfunction in open heart surgery patients. ethods: In our study, we assessed the parameters of postoperative liver dysfunction (serum bilirubin, enzymes levels) and their impact on early clinical outcome after open heart surgery of 97 patients from May 2016 to January 2017. Postoperative hyperbilirubinemia was defined as serum total bilirubin >2.0 mg /dl. Results: The patients were divided into two groups: Group A; CPB time 120 minutes (37.11%), Group B; CPB time >120 minutes (62.88%). Mean total CPB and cross clamp time in group A (96.30 & 65.30 minutes respectively) and in group B (176.06 & 139.49 minutes respectively). High inotropic support, ventilation time, ICU stay, blood transfusions and complications were more in group B. The serum total bilirubin reached its maximum level on the first, second and third postoperative day in 17%, 43%, and 34% in group A and 7%, 64%, 44% in group B patients and hyperbilirubinemia came mainly from indirect bilirubin. The pattern of raised liver enzymes mainly AST on the first, second and third postoperative day in 86%, 86%, and 40% in group A and 87%, 98 %, 64 % in group B patients. Hospital mortality was higher in group B (16.33%) than in group A (5.55%). Conclusions: Postoperative hyperbilirubinemia and significantly raised enzyme mainly aspartate aminotransferase is common in patients undergoing cardiopulmonary bypass on second postoperative day and is predictor of mortality.