Background/Aims: Hepatocellular carcinoma (HCC) has poor long-term prognosis so we need new diagnostic techniques and markers to detect HCC in the early phases. The aim of this study was to analyze the levels of serum mean platelet volume in HCC. Methodology: The clinical data of 230 subjects with normal, chronic hepatitis, cirrhosis and HCC were retrospectively analyzed at our hospital between January 2009 and December 2009. The levels of MPV were determined in patients with liver disease and compared between patient groups and with healthy persons. Results: Serum MPV levels were significantly increased compared to the patients with chronic hepatitis, cirrhosis, and the control group (p<0.01). The cut-off value for MPV for the detection of HCC in cirrhotic patients was calculated as >= 9.2fl using ROC analysis [Sensitivity: 68.3%, specificity: 62.1%, AUC: 0.676 (0.580-0.773), p<0.001]. Additionally, serum MPV levels show higher sensitivity for diagnosis of HCC than AFP. An AFP of more than 7.4IU/mL and an MPV of >= 9.2fl, both put together, had a specificity of 95.2%, while when used separately, they have a sensitivity of 87.5%. Conclusions: MPV may be a potential or adjunctive marker of HCC in patients with chronic liver disease.