BACKGROUND/AIMS: Patients with cirrhosis have increased total blood volume (TBV). The size of the "effective" blood volume has been closely investigated, whereas the distribution of the blood volume outside the thorax has not been examined. The aim was to estimate the blood volume distribution in patients with cirrhosis and portal hypertension, using a dual-head gamma-camera technique (DHGCT) and to validate this technique. METHODS: Twenty-three patients with cirrhosis, 11 non-cirrhotic control patients, and six healthy controls had their blood volume distribution determined by the DHGCT. RESULTS: The close relation between the estimated blood volume in the thorax region and the central and arterial blood volume, obtained by the dynamic indicator dilution technique (r=0.87, P<0.001), indicates validity of the DHGCT. Whole-body scintigraphy showed altered blood volume distribution in the cirrhotic patients with increased splanchnic blood volume (SpBV: 25.0 vs. 18.2% of TBV in controls, P<0.001), and all but one patient with hepatic venous pressure gradient above 12 mmHg had SpBV above 20% of TBV, but the blood volumes in the liver region were similar. CONCLUSIONS: DHGCT is a valid method of estimating the blood volume distribution. Patients with cirrhosis and portal hypertension have grossly increased blood pooling in the splanchnic region, indicating splanchnic congestion.