Parents are aware that young age is a risk factor and are more likely to take an infant to the emergency room than an older child with similar symptoms. It is essential that the physician rapidly responds to the concerns of such parents. It is not possible to exhaustively address in a few pages all of the potential emergency conditions that may arise with infants younger than three months. We therefore focus our discussion to the most frequently occurring emergency conditions. In particular, we emphasize the serious nature of such conditions as fever, apparent life threatening, hyperbilirubinemia, weight loss, and excessive crying.