The specificity of this clinical case is late diagnosis of portal hypertension when confirming the diagnosis in a 12-year-old boy with a history of an acute icteric form of hepatitis G. Against the background of treatment prescribed in accordance with the practice guidelines of the World Gastroenterology Organisation for treatment of hepatitis B (2015) - M.Pevzner diet No 5; hepatoprotective drugs, recombinant human interferon alpha-2 - the boy's general wellbeing improved, total bilirubin nor maised, ALT and AST levels decreased from 1547 and 1265 IU/ml to 78 and 58 IU/ml, respectively; prothrombin index increased from 54% to 72-80%. The diagnosis of disease was considerably complicated by an outright refusal of the patient's parents to undergo liver biopsy, and unauthorized early withdrawal from the antiviral drug worsened the course of disease: 3 months later the boy felt worse. Later on, disease took a wave-like course and was associated with development of asthenic and dyspeptic syndromes, lesions of the bile ducts, intrahepatic cholestasis, persistent cytolysis and severe liver fibrosis (according to elastography - stage F4). Immunological dynamic examination found only positive total antibodies to the surface antigen of the hepatitis B virus, whose titer 12 years after primary vaccination against hepatitis B virus increased from 20 to 40 and 72.2 IU/L. Scanty immunological changes without histological confirmation have not allowed the final verification of diagnosis. Dynamic observation and broadening of the spectrum of differential-diagnostic measures at this stage offer little material to explain the causes of recurrent cytolysis or early formation of liver cirrhosis and portal hypertension. We do not exclude a combined course of chronic hepatitis G against the background of undiagnosed diffuse chronic disease of the liver.