OBJECTIVE Plasma viscosity (PV) is a major determinant of capillary blood flow through the microcirculation, which, if impaired, can result in potentially important clinical sequelae. The objectives of this study were to investigate the alterations of PV values in different stages of cirrhosis, and to determine if any change in PV correlates with Child score or Model for End-Stage Liver Disease (MELD) score or has any prognostic significance. METHODS The study included 92 patients with cirrhosis and 28 healthy volunteers. Upper endoscopic and ultrasonographic examinations of the patients were obtained. Serum biochemistry fibrinogen, complete blood count, C-reactive protein (CRP), and lipid profile were performed. PV was determined using a rotational viscosimeter. RESULTS PV decreased with the progression in Child scores (Child A: 1.46 +/- 0.20 mPa-s, Child B: 1.33 +/- 0.21 mPa-s, Child C: 1.12 +/- 0.15 mPa-s), (P < 0.001). A similar change was detected between the MELD score and PV (P < 0.001). There was a positive correlation between the total protein, albumin and plasma viscosity in the control group, but a similar relationship was not found in cirrhotic patients. History of hepatic encephalopathy (30 of 92 patients) was independently associated with decreased PV (P = 0.003). CONCLUSIONS We observed that increasing Child and MELD scores were significantly associated with lower PV levels irrespective of biochemical and hematologic values. These observations support the concept that hemorheologic changes in cirrhotic patients might be either the cause or the result of a pathophysiological process, and it may not be easy to distinguish between these two possibilities.