Background: Various insults can render the diaphragm weak in ICU patients such as sepsis, electrolyte disturbances, hyperinflation, critical illness polyneuropathy and/or myopathy to name a few out of a long list, Aim: Aim of the work was using ultrasound to assess the function of the diaphragm in the mechanically ventilated pediatric patients. Detect the effect of mechanical ventilation on the infant and pediatric diaphragm muscle. Detect any association between diaphragm dysfunction and poor mechanical ventilation outcome