We have identified eight infants born to mothers who were heavy users of caffeine during pregnancy. These infants exhibited unusual behavior in the immediate newborn period. Predominant symptoms were irritability, jitteriness, and vomiting. The eight infants had extensive diagnostic studies and none of the usual causes for their symptoms were identified. Caffeine was present in the serum of six infants, and three of the six infants had caffeine in their urine. The symptoms resolved spontaneously. We hypothesize that these infants were exposed to high maternal levels of caffeine for the majority of the pregnancy, resulting in a withdrawal syndrome after delivery.