Background Red cell distribution width (RDW) is a marker of red blood cell size heterogeneity. Increased RDW is associated with liver diseases, but it has not been studied in patients with hepatitis C virus (HCV). Aim To determine if RDW is a potential prognostic index for liver diseases due to chronic HCV infection. Patients and methods A total of 95 patients with liver diseases due to chronic HCV infection and 20 healthy controls were enrolled in this cross-sectional study. Patients comprised 20 patients with chronic HCV, 52 patients with HCV-related cirrhosis, and 23 patients with HCV-related hepatocellular carcinoma (HCC). HCV antibody, PCR of HCV, HBsAg, complete blood count, liver function tests, and RDW were assessed. Child–Pugh score were calculated in patients with cirrhosis and those with HCC. Results RDW was significantly increased in patients with HCV-related liver cirrhosis and patients with HCV-related HCC compared with patients with chronic HCV infection and healthy controls (P≤0.05). Moreover, RDW was higher in patients with chronic HCV infection than in healthy controls, but it did not achieve statistical significance (P>0.05). In patients with cirrhosis and patients with HCC, RDW was positively correlated with total bilirubin and Child–Pugh score and negatively correlated with hemoglobin concentration, platelet counts, and serum albumin. Conclusion RDW was increased in patients with HCV-related liver cirrhosis and patients with HCV-related HCC and was correlated with higher Child–Pugh score. RDW could be a valuable prognostic index for chronic liver diseases due to HCV infection.