The course of MIB-1 expression by brain macrophages adjacent to cortical contusions has been immunohistochemically investigated during the first 30 weeks after human brain injury, in order to provide data for a forensic wound age estimation. A positive nuclear staining for MIB-1 could be observed earliest after a postinfliction interval of 3 days and regularly in cases with a survival time between 7 and 14 days, whereas in uninjured brain tissue (control group) no cellular MIB-1 reactivity was visible.