Abstract: Objective: To observe the morphological changes of delayed neuronal death in cerebral hippocampal sections of mice with repeated ischemia-reperfusion. Methods: We made incomplete cerebral ischemia-reperfusion modern through clipping bilateral common carotid arteries repeatedly. At 24 hours,72 hours and 7days After ischemia-reperfusion, we collected mice brains and made sections. These sections were stained by HE, and by the method of terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling（TUNEL）. Results: At 7 days after reperfusion, there appeared diffuse necrosis in hippocampal pyramidal neurons, it is most obvious in CA1 region. By in situ end-labeling of DNA, we can see particular positive particles in some cellular nucleus of granule neurons in dentate gyrus, of pyramidal neurons in the regions of CA2, CA3, and of some neurons in CA1 nearby necrosis neurons. It would be apoptotic cells. Conclusions: Delayed neuronal death existed as two forms of apoptosis and necrosis in the hippocampal sections, necrosis is the main pathological alteration at CA1 pyramidal neurons, whereas apoptosis is obvious at granule neurons of dentate gyrus. The pathogenesis and biological process of delayed neuronal death and its relationship with degeneration of nervous system had been discussed preliminarily.