The aim of this study is estimation of the frequency of nosocomial infections caused by HBV, NANB virus, HCV in health service institutions of Gdańsk province. Relationship between medical procedures and acute viral hepatitis was examined among 4268 patients hospitalized in Clinic of Infectious Diseases and Provincial Hospital of Infectious Diseases in Gdańsk, from 1986 to 1995. The analysis of results showed that 1915 (44.9%) cases of viral hepatitis caused by HBV, NANB virus, HCV were probably connected with diagnostic or therapeutic procedures. Within ten years number of HBV, NANB, HCV infections decreased but at the same time relative increase of nosocomial infections caused by those pathogens was observed. Transfusion anamnesis was noted among 129 patients (8.5% of all persons with acute viral hepatitis probably infected in hospitals).