Introduction. Determination of schedule and certain predictable regularities of ultrastructural changes of proximal tubules epithet of kidney during post mortal interval would be very useful in forensic medicine when it is needed to determine the exact time of death. Material and methods. In this research there were 52 experimental animals, laboratory rats 'Wistar' type, which had been killed by choking. Four animals were selected to be a control group right after death, and 48 rats were divided into three equal groups: The rats were then fended on different temperatures: 8-10°C, 18-20°C, 28-30°C, respectively. In each and every group the rats were divided into four groups based on time interval after death: I, 2, 4 and 6 hours. There were four rats in each of those four subgroups. Preparations were analyzed and photographed using transmission electronic microscope. Results. It was found that pace of ultrastructure changes of proximal tubules epitel the cells of kidney was directly dependable on the duration of autolysis and temperatures that the body was stored at. First changes on nucleus, which are separation of external and internal membranes, occurred during the fourth hour of autolysis. Decomposition of external membrane occurred also during fourth hour on temperatures of 8-10°C and 18-20°C. When the body was stored at 30°C lysised decomposition of both membranes of nucleus and loss of natural nucleus shape were noticeable even during the first hour of autolysis. During the sixth hour nucleus membranes were almost lysised around the perimeter and that led to 'leaking' of chromatin in sarkoplasm. Mitochondria kept their normal shape six hours after death when the body was stored on 8-10°C and 18-20°C, and lysis and fragmentation of cristae were noticeable from the first hour of autolysis. Mitochondria lost their natural shape and inner composition during the first hour when the body was stored at 30°C. So, after the fourth hour only balloon like and light-ened remaining of mitochondria and fragmented pieces of their cristae were noticeable. Conclusion. All of the predictable changes found in morphological changes on subcell level of kidney tissue can be useful to determine very precisely the time of death. They can be also used to determine vital value of tissue and organs.