One of the primary responsibilities of the anesthesiologist is to act as a guardian for the anesthetized patient during surgery. Monitoring of anesthetized patient is designed to collect data that reflect 1- physiologic homeostasis 2- responses to therapeutic interventions 3- proper functioning of anaesthetic equipment. Monitoring provides an early warning of adverse changes or trends before irreversible damage occurs. Improvements in patient safety follow introduction of monitoring during anesthesia, the most important monitor in the operating room is the vigilant anesthesiologist. In case like cardiac patient, not only intraoperative monitoring but also an appropriate pre and postoperative monitoring are important. Monitoring of cardiac patient:In case like cardiac patient, not only intraoperative monitoring but also an appropriate pre and postoperative monitoring are important. The choice of the monitoring equipment requiring meticulous understanding of the patient underling path-physiological status, concomitant organs dysfunction, nature of the procedure and its hazards. Postoperative monitoring of cardiac patients : The patient is in the postoperative period should be monitored to find and treat life threatening problems that are present or evolving, and to help prevent major morbidity and mortality in patients at high risk. Monitoring of pediatric patient:Monitoring of pediatric patients should be the same as for adult patients undergoing comparable types of surgery.