An anesthetized endotoxemic baboon model has been developed by infusing 2.0 mg E. coli endotoxin/kg i.v. over 1 hr (n = 7). Animals were monitored for 5-7 days with analyses of: cardiovascular, metabolic, and organ dysfunction; acid base, hemostatic, and hematological alterations; as well as tumor necrosis factor (TNF) and interleukin-6 (IL-6) levels. Pathophysiologies detected at 2 hr included transient decreases in vascular resistance and blood pressure, a 157% increase in blood lactate, and a 90% decrease in circulating neutrophils. Organ dysfunction was not observed until 24 hr and, although thrombocytopenia was prevalent (-72% at 48 hr), disseminated intravascular coagulation (DIC) was not a major pathology. Hematocrit fell 21% by 24 hr and was -41% at 5-7 days. Serum TNF peaked at 90 min (7.8 +/- 0.2 ng/mL) and was undetectable after 3 hr. IL-6 also increased early, peaked at 3 hr (3872 +/- 846 U/mL) and was still detectable at 24 hr. A low mortality primate model of gram-negative sepsis has been developed that is characterized by early cardiovascular and metabolic dysfunction (2-6 hr), late organ dysfunction (24-48 hr), sub-clinical DIC, a prolonged anemia, and a 29% mortality between 48 and 72 hr.