Endotoxin infusion (lipopolysaccharide from Escherichia coli 120 μg kg–1 i.v.) was titrated to produce hypercoagulability in rabbits and the effects of prostacyclin (PGI2) treatment (continuous infusion of 6 ng kg–1 min–1 i.v.) on coagulation variables, cardiorespiratory variables, and fibrin deposition in the microcirculation of vital organs were studied. PGI2 infusion did not influence the concentration of soluble fibrin, throm-belastographic variables, or systemic platelet aggregability. Fibrin deposition in the microcirculation of the liver and the lungs was reduced to 50% of that observed in untreated animals (p < 0.01). The antiplatelet properties of PGI2 were unable to reduce experimental endotoxin-induced systemic procoagulant turnover but improved organ perfusion during the initial phase of disseminated intravascular coagu