Eleven of 19 sick newborn infants were shown to have either laboratory and/or pathologic evidence of disseminated intravascular coagulation (DIC) during an observation period of 8 months. Three of the affected infants had severe viral diseases (rubella, cytomegalic inclusion virus, and herpes simplex). Seven of the infants had severe idiopathic respiratory distress syndrome (IRDS), and one infant (the product of a severely toxemic mother) had transient respiratory distress. The remainder of the sick infants had mild IRDS without evidence of DIC. Diagnosis of DIC in the newborn is best made by reliance upon specific clotting factor assays (platelets, fibrinogen, and factors V and VIII) rather than nonspecific screening tests or presence of fibrin degradation products. DIC may be a more common complication of severely ill newborn infants than is generally realized.