Oogenesis is an important physiological event in the process of reproductive development.The present study was undertaken to investigate the apoptosis of the cells on fetal porcine ovaries.The fetal porcine ovaries 33,40,46,54 and 61 days post coitum (dpc) were collected from pregnant sows,respectively,and the paraffin sections were prepared and then stained by fluorescent dye Hoechst 33258.The results showed that the apoptotic cells were observed since 33 dpc in primordial germ cells and oogonium,and the apoptosis rates were 3.13%,4.32%,5.50%,9.43% and 11.10% at 33,40,46,54 and 61 dpc respectively.Meanwhile,the apoptosis rates of granulosa cells were 8.89%,12.45%,14.74%,17.96%and 22.81% at 33,40,46,54 and 61 dpc respectively.These results suggest that the apoptosis of oogonium and follicle cells on fetal porince ovaries happens and increases at the early stage of oogenesis.