OBJECTIVE To studyassociations between clinical signs and results of serological and molecular biological tests in patients with different clinical variants of chronic HCV-infection. METHODS Two hundred twenty-five patients with various clinical course of chronic hepatitis C was tested on the presence of serological markers of HCV-infection, their combinations and HCVRNA. RESULTS HCV RNA was detected in 78% of patients. Rate of detection of IgM to cor-antigen was higher in RNA HCV-positive patients, which also had higher detection rate of IgG to non-structural viral protein. Anti-cor IgM antibodies were detected more often than others irrespectively from clinical manifestations of the disease. CONCLUSIONS Association between results of serological as well as molecular biological tests and detection of active viral replication in patients with chronic HCV-infection was established. RNA HCV is significantly more frequently detected in serum samples which contain broad spectrum of antibodies to HCV irrespectively from clinical manifestations of the disease. This is important for optimization of diagnostic and treatment measures in practice.