The role of exchange transfusion with fresh whole blood in septic shock infants was evaluated. Endotoxin was positive in 8 of 10 infants and completely removed from 6 by exchange transfusion. All 6 infants with negative endotoxins after exchange transfusions survived, but 2 with positive reactions died despite the exchange transfusion. Staphylococcus aureus was cultured in the blood from 2 infants with negative reactions and one of them survived. These findings suggested that the clearance of endotoxin has an important role in exchange transfusion among septic shock neonates.