Thrombocytopenia is a common complication of chronic liver diseases, but its pathogenesis is not clear. Although generally attributed to hypersplenism, other factors should also be considered. We investigated the relationship between the peripheral platelet count and the degree of fibrosis in patients with chronic viral hepatitis. In an effort to avoid the effects of hypersplenism, we excluded patients with splenomegaly and/or bi- or pan-cytopenia. Seven hundred eighty-four patients (265 chronic viral hepatitis C and 519 chronic viral hepatitis B) were included in the study. Univariate analysis showed that the peripheral platelet count had a negative correlation with fibrosis score, necroinflammatory activity, and age in both groups. In multivariate analysis, the peripheral platelet count had a similar correlation with the fibrosis score and age, but not with necroinflammatory activity, in both groups. The peripheral platelet count decreased more significantly in females with chronic hepatitis C but not in the chronic hepatitis B group. In conclusion, a decrease in peripheral platelet count may be a sign of an increase in the degree of fibrosis during the course of chronic viral hepatitis B and C and factors other than hypersplenism may play a role in this decrease in the peripheral platelet count.