Fourty wistar rats were used for experimental study of myocardial infarction (MI )induced by ligation of the left coronary artery. The results showed that the AF and HBFP stalng as well as Ao fluorescence were sensitive in demonstrating the early MI changes occuced 1 ~ 2 hour after coronary arteryligation. The TTC stamg method was reliable for demonstrating the MI margin. Both HBFP and AOfluorescence were under no influeence of the post-mortem autolysis, but the AF reaction were undeithe influence of the early post-mortem autolysis. Four hours were required for complete developemenof MI. The early stage of MI demonstrated by SEM was conslstant with that bv TEM. Both resuhwere influenced by the post-mortem autolysis.