To improve the possibilities of delimitating the time of death after longer laytime it was examined if this is possible by immunohistochemical detection of calcitonin. The results show that in our examination material the c-cells of the thyroid glands of up to 4-day-old corpses produce a positive immunoreaction towards calcitonin in all cases whereas none of the corpses older than 13 days show such a reaction. This means that in the case of a negative immunoreaction the time of death can be assumed to lie >4 days before the autopsy. The fact that a negative immunoreaction occurred consistently after 13 days leads to the conclusion that when calcitonin has been stained in a specimen, the death of the respective person must lie a maximum of 12 days earlier, whereby these time-limits may change in considerably different surrounding conditions.