Abstract: Objective To observe the variation of endogenous Apelin with its APJ receptor on the model of rats with septic shock are caused by cecal ligation and puncture (CLP). Methods: Twenty male Wistar rats weighting 200~250g randomized into two groups; control group, severe septic shock group. Enzyme immunoassay (EIA) was used to detect levels of Apelin in plasma and myocardia. RT-PCR was used to analysis the relative amount of mRNA of Apelin and APJ in the myocardia. Western blot was used to determine the protein levels of myocardial APJ. Result: Compared with sham, rats with sepsis showed inhibited cardiac function (+LVdP/dtmax and -LVdP/dtmax decreased, and LVEDP elevated). Rats with septic shock showed significant hypoglycemia and hyperlacticaemia, lower levels of Apelin in plasma and myocardia, decreased mRNA relative amount of Apelin and APJ in the myocardia, and lower myocardial APJ protein level. Conclusion: Apelin and its receptor might play an important role in septic shock.