This study investigated regional cerebral blood flow in head-injured patients using statistical parametric mapping (SPM) to detect hypoperfusion on Tc-99m-hexamethylpropyleneamine oxime (HMPAO) SPECT scans. Methods: Acute and follow-up SPECT and MRI scans from 61 patients who were admitted to a regional neurosurgical unit were examined. Patients had acute MRI and SPECT at 2-18 d after injury and on follow-up between 130 and 366 d after injury. Thirty-two scans from non-head-injured patients were used as a SPECT control group. The SPECT images were first aligned to the Talairach-Tournoux atlas and then analzed statistically with SPM. Results: SPECT detected more extensive abnormality than MRI in acute and follow-up stages. This effect was more pronounced on follow-up of patients with diffuse injury. Examination of a focal injury group indicated the involvement of frontal and temporal lobes and the anterior cingulate. Blood flow abnormalities persist, to a lesser extent, on follow-up scans, The diffuse group displayed low blood flow in the frontal and temporal lobes, including cingulate involvement, which persists at follow-up with additional involvement of the thalamus. Conclusion: SPM has a role in SPECT image interpretation because it allows better visualization than other methods of quantitative analysis of the spatial distribution of abnormalities in focal and diffuse head injury. Frontal lobe blood flow abnormality (particulary anterofrontal regions and mesiofrontal areas) is common after head injury.