INTRODUCTION AND AIMS: The crucial role of calcium in cardiac muscle contraction and calcium-dependent signaling in the heart has been appreciated for decades. Decreased myocardial performance, conduction abnormalities, dysrhythmias, such as heart block and ventricular dysrhythmias,congestive heart failure, hypotension and other significant cardiac abnormalities have been reported in patients with hypocalcemia. However, influence of preoperative calcium on outcomes of cardiac surgery has never been evaluated.