Of 107 patients admitted to the South Western Hyperbaric Medical Centre with acute carbon monoxide poisoning for hyperbaric oxygen therapy 19 had cerebral imaging performed: 17 patients had CT, one patient had MRI and CT and one patient MRI alone. The role of brain CT is established in determining the prognosis from acute carbon monoxide poisoning. Brain imaging was indicated because of unconsciousness on admission and failure or delayed improvement in neurological status after initiation of hyperbaric oxygen therapy. Of the 18 patients who underwent brain CT, seven were found to have the characteristic changes of bilateral low attenuation areas within the globus pallidus and six had low attenuation changes within cerebral white matter. In two patients there were both globus pallidus and cerebral white matter changes. Out of the total of the 19 patients who were studied, four patients died, 10 recovered fully and five had variable disabilities ranging from short term memory loss to more severe cognitive impairment and physical disability. The role of CT and the practicalities of hyperbaric oxygen therapy for acute carbon monoxide poisoning are discussed in the light of the experience from a regional dedicated medical diving centre.