Background: The mean platelet volume (MPV) is the most commonly used measure of platelet size and is a potential marker of platelet reactivity. In this study, we aimed to explore the relationship between hepatic histopathology in viral hepatitis and MPV levels, which are associated with platelet count and activity. Materials and Methods: We performed a retrospective case-control study of baseline histological and clinical parameters in chronic hepatitis B and C patients in our tertiary reference center between January 2005 and January 2011. Two hundred and five chronic hepatitis B patients and 133 chronic hepatitis C patients who underwent liver biopsy were included in the study. The patients were divided into two groups: Chronic hepatitis B and chronic hepatitis C and were additionally divided into groups of two according to histological activity index (HAI) and fibrosis scores obtained by liver biopsy results (according to the Ishak scoring system). The clinical characteristics of chronic viral hepatitis patients, including demographics, laboratory (especially MPV), and liver biopsy findings, were reviewed. Results: One hundred and forty-three patients were male (69.1%), and the mean age was 41.9 +/- 12.75 with an age range of 18-71 years in hepatitis B patients. In the classification made according to HAI, 181 patients were in the low activity group (88.3%) and 24 in the high activity group (11.7%). In the evaluation made according to fibrosis score, 169 patients were found to have early fibrosis (82.4%) and 36 were found to have advanced fibrosis (17.6%). In patients with hepatitis B, there was no statistically significant difference in terms of their MPV values between the two groups, separated according to their degree of activity and fibrosis. Sixty-three patients were male (47.3%), and the mean age was 50.03 +/- 12.75 with an age range of 19-75 years. In the classification made according to HAI, 109 patients were in low activity group (81.9%) and 24 in high activity group (18.1%). In the evaluation made according to fibrosis score, 101 patients were found to have early fibrosis (75.9%) and 32 have advanced fibrosis (24.1%). There was a statistically significant difference between the activity and fibrosis groups of the hepatitis C patients (P = 0.04 and P = 0.02, respectively). Conclusion: MPV values are more reliable in hepatitis C patients than hepatitis B for predicting the advanced damage in liver histology. This finding might be useful for the detection of early fibrosis and also starting early treatment, which is important in hepatitis C.