Acute inflammatory response occurring in cardiopulmonary bypass (CPB) patients has been clearly associated with deleterious clinical outcomes. Increasing understanding of the pathophysiology of systemic inflammatory response syndrome (SIRS) following CPB has facilitated the development of strategies to attenuate the damaging effects of cytokine-induced inflammation. For any strategy to be tested, one needs to clearly define and understand the inflammatory response occurring with CPB. Although this has been extensively studied, there is wide variation in the reported time course and magnitude of this response. This variation is, in part, due to the heterogeneous nature of the patient population studied (variable severity of illnesses, ejection fractions, co-morbidities, etc.). Hence, in our study, we propose to study the inflammatory response occurring in patients undergoing coronary artery bypass graft (CABG) with and without the use of CPB in our institution, and to determine whether the severity of inflammatory response seen in CABG patients is associated with impairment of any specific clinical parameter in the immediate post-operative period (i.e., ventricular dysfunction, lung injury, bleeding, renal failure, etc).