In the injured mouse cerebral hemisphere changes in the number and distribution of immunoglobulin G (IgG)-containing cells were examined. First IgG-immunopositive cells appeared close to the edge of lesion 10 min. following the injury. The total number of IgG-containing cells and the size of area occupied by them were maximal on the 1st posttraumatic day and then gradually decreased. However, 30 days after injury few IgG-immunopositive cell were still visible close to the injury site.