Sepsis of the newborn induced by gram negative bacteria, especially E. coli is often accompanied by a severe coagulation disorder. It can be treated by blood exchange transfusion (ET) with heparinized blood. In this study the hematological effect obtained by the exchange transfusion was investigated in rabbits after induction of a generalized Shwartzman reaction by two spaced injections of endotoxin (75 microgram/kg) 24 hrs. apart. Three groups of 6 animals each were investigated: group I: without endotoxin but with ET (controls); group II: endotoxin without ET; group III: endotoxin with ET. Fibrinogen, soluble fibrin monomer complexes (SFMC), fibrin(ogen) degradation products (FDP), platelet- and leukocyte counts and urine volume (ml/hr) were estimated. In group II a decline in the fibrinogen level, and in platelet and leukocyte count, as well as an increase in SFMC and FDP could be observed from 6 hrs. on after the second endotoxin injection. In group III 6 hrs. after the second endotoxin injection, exchange transfusion with heparinized blood was performed. Variance analysis showed significant differences in all parameters, except in the urine volumes after exchange transfusion between group III and group II. By exchange transfusion an approach of the values towards the values of the controls could be recognized. The findings indicate, that by blood exchange transfusion the hematological consequences of the endotoxin induced DIC can be corrected, while the dysfunction of the kidneys can be improved only slightly.