OBJECTIVE: To investigate the mechanism of severe myocardial contusion in rabbits. METHODS: A total of 32 New Zealand rabbits were randomly divided into 2 groups, the severe myocardial contusion group (the experimental group, n=16) and the sham-impact control group (the control group, n=16). Hemorheological parameters, interleukin-8 (IL-8) in serum, the water contents of myocardium and polymorphonuclear neutrophil (PMN) infiltration in contused myocardium were observed at 24 hours after the experiment. RESULTS: As compared with the control group, the hemorheological parameters in the experimental group including the whole blood viscosity (etab), erythrocyte aggregation index (EAI), hematocrit (HCT), serum fibrinogen (Fib), Casson viscosity (Gammay) and erythrocyte sedimentation rate (ESR), significantly increased. The IL-8, PMN infiltration and the water contents of the contused myocardium also significantly increased. CONCLUSIONS: It suggests that the hemorheological disorder, increase of IL-8 in serum, and PMN infiltration in contused myocardium may contribute to the development of cardiac edema and secondary myocardial damage following severe myocardial contusion in rabbits.