OBJECTIVE Alterations of regional cerebral blood flow (rCBF) in subjects with liver cirrhosis have not been fully evaluated. We evaluated quantitative changes in rCBF using single photon emission computed tomography (SPECT). METHODS Twenty-eight Japanese patients with liver cirrhosis were enrolled in this study. None of them exhibited advanced hepatic encephalopathy at the time of examination. The cause of liver cirrhosis was viral infection in 26 patients; the cause was unknown in two patients. Child-Pugh classification of the patients was as follows: Group A, 12 patients; Group B, 12 patients; and Group C, four patients. The control group consisted of 25 age-matched healthy subjects. Radionuclide angiography was performed by rapid injection of Tc-99m ethyl cysteinate dimer (ECD) (740 MBq) via the right cubital vein, and then SPECT brain images were taken. Using the Patlak graphical method, rCBF values (ml/100 g per min) were calculated in the frontal, parietal, temporal and occipital lobes and cerebellum on SPECT images. RESULTS The rCBF values were lower in cirrhotic patients than in controls, i.e. by 15% in the frontal lobe, by 12% in the parietal lobe, by 10% in the temporal and occipital lobes, and by 7% in the cerebellum. They decreased concomitantly with the severity of liver disease. A significant negative correlation was noted between rCBF values and Child-Pugh score in the frontal (P<0.01), parietal (P<0.05) and occipital lobes (P<0.01). rCBF values of each region were not correlated with age or with results of neuropsychological test. The degree of association between rCBF values and results of laboratory examination was generally poor. CONCLUSIONS Patients with liver cirrhosis without advanced encephalopathy showed widespread reduction in rCBF; this reduction was particularly evident in the frontal lobe. Tc-99m ECD SPECT may be useful for evaluating cerebral functional changes in patients with liver cirrhosis.