To investigate the postmortem changes in hepatic cell membrane, the rats were sacrificed with cervical dislocation and kept in an incubator at $25^{circ}C$, 70% of humidity for 12 hours. The biochemical experiments in postmortem were done at 2, 4, 8 and 12 hours. The degree of rigor mortis and algor mortis were increased with the time during 12 hours. The contents of hepatic malondialdehyde were rapidly increased ai 2 hours, and gradually decreased afterward. In histological findings, after 8 hours, the clotted blood was seen in central vein and sinusoids, and especially portal veins were dilated a1though the structure of hepatic lobules was preserved well. Furthermore, both in the histochemical and enzymatic examinations, membrane bounding alkaline phosphatase activities were gradually decreased with the time. In conclusion, the activity of membrane bounding alkaline phosphatase was linearly decreased with time in the early postmortem period and so it might be referred to the possibility fur the estimation of death time in the early postmortem period.