A patient with hepatic encephalopathy is described. An initial SPECT using Tc-99m HMPAO was performed to evaluate relative brain perfusion. The initial brain SPECT images revealed decreased perfusion in the left frontal temporal lobe region. A subsequent carotid Doppler study revealed left-sided carotid artery stenosis. After appropriate medical treatment for elevated NH(3) levels and reversal of the patient's symptoms, repeat SPECT brain images showed a normal pattern of activity. The possible causes and significance for these image findings are discussed.