The changes of retinal nuclear DNA content in rats after death was detected and the relationship between degradation of retinal nuclear DNA and postmortem interval (PMI) was analyzed. Ninety healthy adult SD rats, female, weighing 250+/-10 g, were randomly divided into 15 groups. At 20 degrees C, the retinal cells were withdrawn every 2 h within 0 to 28 h after death and stained with Feulgen-Vans. Index of density (ID), integral absorbance (IA) and average absorbance (AA) in retinal nucleus were analyzed by image analysis system. And the obtained data were subjected to linear regression analysis by using SPSS12.0 software. The results showed that in retinal nucleus, AA and IA were gradually declined with the prolongation of PMI, while ID had an increased tendency. Within 28 h after PMI, the regression equations were as follows: Y(AA )=-0.009X(AA )+0.590 (R(2)=0.949), Y(IA )=-0.097X(IA )+18.903 (R(2)=0.968), Y(ID)=0.122X(ID)+2.246 (R(2)=0.951). It was concluded that retinal nuclear DNA after death in rats was degraded gradually and had a good correlation with PMI.