During 12 months after allogenic bone marrow transplantation abnormal liver function tests are observed in the majority of patients.In our study we observed 4 patients (3 males and 1 female)aged 36 –44 years,mean 40 with symptoms of cholestatic acute hepatitis after allogenic bone marrow transplantation due to chronic myeloid leukaemia.These patients were admitted to the hospital with suspicion of acute viral hepatitis.The allogenic bone marrow transplantation was performed 120 –450 days (mean 223)before admission to hospital.In all cases we observed classical ’symptoms of GvHD (cutaneus eruption,mucosal erosions and pulmonary fibrosis) before symptoms of liver injury appeared.Viral hepatitis (HAV,HBV,HCV,CMV)and liver damage due to bacterial or fungal infection and drug toxicity were excluded.The mean value of liver function tests were as follow:ALT 1410 IU/l, bilirubin 2.5 mg/dl,Alkaline phosphatase 272 IU/l,GGT 499 IU/l.Histopatologic examinations of liver biopsy specimens revealed parenhymal necrosis with lymphocytic infiltration of partial zones and perivascular, periportal fibrosis.In liver samples the typical changes of GvHD in small bile ducts were found.In all cases immunosupressive therapy (corticoids, cyclosporine)was effective. Conclusions: The acute hepatitis as a form of liver manifestation of chronic GvHD should be taken under consideration during diagnosis of acute viral hepatitis after bone marrow transplantation in patients on mild immunosupression. High-dose immunosupression seems to prevent the progression of intrahepatic bile ducts ’destruction effectively.Liver biopsy is crucial in diagnosis of GvHD.