Hemorrhagic liver necrosis of varying degrees of severity was observed in 22 (32.8%) of 67 newborn infants with idiopathic respiratory distress syndrome (IRDS) given tromethamine (Tris) and sodium bicarbonate buffers via the umbilical vein for treatment of respiratory acidosis. Identical solutions, if injected via the umbilical artery, were not associated with liver injury. Nor was liver damage observed if bicarbonate alone was injected via the umbilical vein. It is doubtful whether liver injury was a crucial factor leading to death in these seriously ill infants. However, it is felt the long-term consequences of such extensive liver damage may be serious for the survivors.