Objectives: This study was designed to evaluate the applicability of anesthetic myocardial protection (pre-conditioning and minimization of reperfusion injury) using two anesthetic regimens on plasma levels of cardiac troponin T (cTnT), as a marker of myocardial ischemia, in pediatric patients assigned for surgical correction of congenital heart diseases using cardiopulmonary bypass (CPB). Patients & Methods: The study included 60 patients (36 males and 24 females). Patients were randomly allocated in 2 equal groups: Midazolam group received a continuous infusion of midazolam (0.2 mg/kg/hour) and Isoflurane group maintained by an end-tidal concentration of isoflurane of 1-1.5% throughout the operation. Six blood samples were taken for estimation of plasma cTnT levels immediately after induction of anesthesia, (S1), 8-hours (S2), 16-hours (S3), 24-hours (S4), 36-hours (S5) and 48-hours (S6) after aortic cross-clamping. Results: Plasma cTnT levels estimated after aortic cross-clamping (S2-S6) showed a significant (P1