BACKGROUND Chronic hepatitis C is a progressive liver disease. It may lead to cirrhosis within 15-20 years, on the grounds of which hepatocellular carcinoma may develop in around 4% of the cases. The entity can thus be regarded a premalignant condition. Based on the above, early diagnosis is of great importance, as is prompt treatment. OBJECTIVE 1. to find correlations between the activity grade, stage of the disease and the various histologic characteristics, which are befitting representations of the clinical course for chronic hepatitis C, 2. to collect data on changes of nuclear proteins as markers of cell proliferations, 3. to analyse the changes in the expression of the components of the extracellular matrix, which play role in the pathogenesis of the fibrosis. RESULTS Analysing the 106 biopsy specimens most frequently mild degree of inflammation was found. The majority of cases were in stage 1 (41.5%), however 8.69% were already in stage 4. Lymphoid aggregates/follicles and bile duct lesion were in correlation with the activity of the disease. A considerable decrease in the ALT level and in the histologic activity was induced by the 12 months interferon-alpha treatment. A positive correlation was found for the expression of the nuclear proteins used as proliferation markers in minimal and mild activity cases, while in moderate chronic hepatitis C a remarkable decrease was manifest in respect to cyclin-A activity. After 12 months IFN-alpha treatment the proliferating cell nuclear antigen activity increased, with a decrease in cyclin-A positivity. CONCLUSIONS Chronic hepatitis C cases with mild activity may also belong to stage 4, the need for liver biopsies should therefore be considered even besides the presence of near normal biochemical parameters in certain cases. The positive correlations between lymphoid follicles/aggregates, bile duct lesions and chronic hepatitis C activity refers to the fact that the above noted histologic differences may be evaluated as prognostic factors. The 12 months interferon-alfa treatment has a moderating effect on cell proliferation, as shown by the lowered cyclin-A expression and does have an effect on particular components playing role in the early phase of fibrogenesis.