Among problems that are faced by the expert while passing opinions in civil cases regarding claims for compensation in infections by HBV and HCV, one of the most important issues is the estimation of the percentage of detriment to health. The analysis of records of proceedings in these cases shows considerable latitude on the part of experts and a high divergence of expert opinions. In their practice, the authors have encountered 12 documented and clinically confirmed cases of chronic virus hepatitis B and C associated with extrahepatic conditions that were causatively associated with chronic infections. Such extrahepatic manifestations included thyroid dysfunctions, renal failure due to glomerulonephritis, dermatoses, hematological conditions or periarteritis nodosa. The authors point out that in spite of a high risk of the development of extrahepatic complications in HBV/HCV patients, or even in view of an existing justified suspicion of the patient suffering from such complications, as a rule no detailed diagnostic management is carried out aiming at detection of possible late health-associated effects resulting from a chronic HBV and HCV infection. As a rule, such complications are diagnosed very late in the-course of the underlying disease and in the majority of cases are regarded as independent of hepatitis. Extrahepatic lesions undoubtedly significantly increase the percentage of detriment to health. In the investigated cases, the percentage of detriment to health was assessed as ranging between 40 to 100%.