Hypovolemia is common during surgery in children patients under anesthesia and may cause organ underperfusion and ischemia. After induction of general anesthesia, children are at particular risk of developing hypotension because of the cardiovascular depressant and vasodilatory effects of anesthetic agents, Ultrasound measurement of the IVC has been studied extensively as a predictor of fluid responsiveness in different clinical settings, so we decided to investigate the use of ultrasound measurements of inferior vena cava (IVC) diameter as predictor of intraoperative hypovolemia.