The postmortem interval is estimated based on physical,biochemical, and morphologic changes in dead bodies, sceneinvestigation findings, and judicial investigation findings. Many factorsaffect the onset and the course of the postmortem changes. There is noestablished method for accurate estimation of the postmortem interval,especially with regard to putrefied dead bodies. Biochemical analysis ofpostmortem body fluids offers an alternative to highly environmentallydependent indicators. The huge literature, especially on chemical methodsof estimating the time since death is still increasing.With the combinationof postmortem biochemistry, histology, immune -histochemistry andmolecular pathology the forensic pathologist has valuable tools to solveunclear cases. Although many methods for determining time since deathhave been proposed, there is still a need to establish more reliable dating techniques.