To observe the change in plasma endotoxin and cytokine during the early period of intra-abdominal infection (IAI) complicated by multiple system organ dysfunction (MSOD) in animals. Twenty rabbits were randomly divided in to two groups. One group received the operation of cecal ligation plus puncture (CLP) inducing IAI complicated by MSOD, and another group received sham operation as a control. All animals were placed in metabolic cages and maintained with intravenous infusion for one week. Plasma levels of endotoxin and cytokine (TNF, IL-1, IL-6) were determined seperately at the beginning (0 hour) or 1, 2, 3, 4, 5, 6 and 24 hours after CLP. Blood bacteria cultures and pathological examination of several organs were made when the animal was dead or killed. Results: The levels of plasma endotoxin, TNF and IL-6 were found to be significantly increased at one or two hours after CLP, the incidence rate of bacteriemia was 80% and the pathological alterations in the abdomen and organs were remarkale, with an average survival time of 84.1±39.0 hours in CLP group. No change in plasma IL-1 level was found in the CLP group. Conclusion: The plasma levels of endotoxin and cytokine (TNF and IL-6) do increase in the early period of IAI complicated by MSOD, and the change in plasma IL-1 is not obvious.