The effects of anti-rhTNF alpha monoclonal antibody (McAb) on oxygen extraction in endotoxemia rabbits were observed by decreasing total oxygen delivery (DO2) with progressive hypoxia. The result showed that the DO2-VO2 relationship in anti-rhTNF alpha McAb group, like the control group, could be clearly divided into "independent" and "dependent" segment, while the non-correlated antibody group, like the endotoxemic group, never presented any plateau upon breathing the air. Critical oxygen delivery (DO2C) and pooled oxygen extraction rate (ER) in anti-rhTNF alpha McAb group were respectively 10.18 +/- 3.21 ml/(min.kg) and 0.690, not significantly different from those in the control group (10.18 +/- 1.69 and 0.730). The ER in non-correlated antibody group was 0.408, which was significantly lower than that in anti-rhTNF alpha McAb group (P < 0.05), while the plasma TNF alpha concentration was significantly higher (P < 0.01). It was concluded that the monoclonal antibody of recombinant human tumor necrosis factor could block or even reverse the pathologic process of oxygen extraction deficiency caused by endotoxemia.