P>Background: Cerebral injury is a well-known complication after cardiac surgery with cardiopulmonary bypass (CPB), especially in adult patients. Specific biochemical markers like neuron-specific enolase (NSE) and S-100 beta protein were developed previously for early detecting neuronal damage after CPB. Corticosteroids are shown to reduce multisystemic deleterious effects of cardiopulmonary bypass due to their anti-inflammatory characteristics. The aim of this study is to demonstrate the decrease of serum neuron-specific enolase levels in patients who received corticosteroids before CPB. Methods: Thirty patients scheduled for elective coronary bypass surgery were included in the study. Patients were divided randomly into two groups as the control group (n = 15) who underwent a standard coronary bypass surgery without any additional medication and the study group (n = 15) who received 1 gm of methylprednisolone before CPB. Blood samples for analysis of serum NSE, interleukin-6 (IL-6), and IL-10 were drawn before CPB, 4 and 24 hours after the end of extracorporeal circulation. Results: Serum cytokine and NSE levels were significantly increased after CPB above their normal range in both groups. In the study group, IL-6 and NSE levels were significantly reduced while IL-10 levels were much higher after CPB. High NSE levels significantly correlated with IL-6 levels in the control group. Conclusion: The lower levels of NSE in patients who received methylprednisolone may suggest that corticosteroids might be useful in decreasing possible neuronal damage during heart surgery. However, we were not able to demonstrate an adverse neurological outcome.