The purpose of this study was to assess the relative incidence of chronic hepatitis in a population of patients with chronic liver disease and to determine the etiological spectrum of this syndrome with special reference to its defined histopathological forms. Histopathology aided by immunohistochemistry, and serology aided by the PCR method were employed in studies of liver biopsy specimens and serum samples, respectively. Out of 1150 patients with chronic liver disease examined, chronic hepatitis was diagnosed in 685 (60% of all cases examined). In this group, there were 308 males aged 18-74 yrs (mean 32 yrs), 153 females aged 18-71 yrs (mean 43 yrs), and 213 children aged 1-17 yrs (mean 8 yrs). Viral infections documented in these patients included HBV (50.4%), HCV (36.2%), HBV/HCV (7.2%) and HBV/HDV (0.7%); cryptogenic and autoimmune hepatitis (AIH) accounted for 2.9% and 2.6% all cases, respectively. In the group of minimal hepatitis (16.1%), HBV infection was documented in 66.4% of cases, HCV-in 29.1%, HBV/HCV-in 3.6% (one case of AIH was included into this group). In the group of mild hepatitis (44.2%), HBV infection accounted for 47.3% of cases, HCV-for 41.9%, HBV/HCV-for 9.9%, and 0.9% was diagnosed as cryptogenic. In the group of moderate hepatitis (19.6%), HBV infection accounted for 50% of cases, HCV-for 37.3%, and HBV/HCV-for 4.5%; cases of cryptogenic and AIH accounted for 3.7% and 4.5%, respectively. In the group of severe hepatitis (20.1%), HBV etiology was found in 44.9% of cases, HCV-in 28.3%, HBV/HCV-in 6.5% and HBV/HDV-in 3.6%; cryptogenic and AIH accounted for 6.5% and 8.0% of cases, respectively. There was a high incidence of low-titer autoantibodies (SMA, ANA and LKM) ranging from 75% in cryptogenic hepatitis and 51% in each HBV and HBV/HCV hepatitis to 46.3% in HCV hepatitis.