We discuss the basic questions concerning hepatitis C virus (HCV) infection and describe the molecular biological and epidemiological features of the causative agent HCV, as well as the pathogenetic mechanisms of the HCV-related hepatic and non-hepatic diseases. We then summarize the diagnostic and therapeutic procedures in accordance with the recent literature. All the problems are discussed from the point of view of Hungarian hepatologists who have given an account of the experiences and possibilities concerning these fields in Hungary.