Cerebral SPECT studies with N-isopropyl-iodo-amphetamine (123I) (IMP) were performed in patients who had suffered cranio-facial trauma, with and without loss of consciousness (LOC). The results were compared with computed tomography (CT). Nine out of ten of those with LOC had normal CT scans and evident photopaenia in IMP studies. It is clear that IMP SPECT scans complement CT in the investigation of patients who have suffered cranio-facial trauma.