We examined 10 histomorphological alterations of 222 cases of subdural hemorrhages following mechanical closed brain injury (MBI) to determine the posttraumatic interval (PTI). These morphological features included red blood cells (RBCs), polymorphonuclear leukocytes (PMNs), macrophages (Ms), RBC-containing Ms, hemosiderin-containing macrophages, hematoidin, fibroblasts, endothelial cells, collagenous fibers and membrane formation. The interval between the time of brain injury and death ranged from a few minutes to 33 years. Following routine staining and immunohistochemical staining of macrophages (CD68), paraffin sections were examined by light microscopy for the presence of the selected histomorphological features. An apparent correlation was found between the frequency of a given histomorphological phenomenon and the length of the PTI. Half of the cases (group 1; n=111) were used to develop a multistage evaluation system, the other half (group 2; n=111) to check its accuracy of prediction. Applying this multistage evaluation model and a special software, 85 of the 111 control group cases (76.6%) could be correctly classified and further 21 cases (18.9%) being assigned to an interval close to the correct interval. Therefore, classification of the correct PTI or an interval close to the correct PTI could be achieved in 95.5% of all cases.