Meconium is the first intestinal discharge of the newborn infant. In addition to epithelial cells, fetal hair, mucus, and bile, meconium also contains a number of proinflammatory components. With the passage of meconium in utero, the meconium-stained amniotic fluid (MSAF) may be aspirated. The presence of meconium in the trachea can cause airway obstruction and, with aspiration below the vocal cords, further obstruction, air trapping, and an inflammatory response, all of which can result in severe respiratory distress. All infants with meconium-stained amniotic fluid do not develop meconium aspiration syndrome (MAS). Hallmarks include early onset of respiratory distress in an infant with MSAF who presents with poor lung compliance, hypoxemia, and a characteristic lung radiograph.