The case of a young woman with GB virus C/hepatitis G virus (GBV-C/HGV) infection and with a severe exacerbation of chronic hepatitis of unknown etiology during pregnancy is described. In the offspring, severe neonatal hepatitis with subsequent mild chronic liver disease of at least 16-month duration was followed by the development of antibodies to the envelope protein (E2) of GBV-C/HGV, suggesting that the child was recovering from GBV-C/HGV infection. There was an improvement in clinical and biochemical parameters in the mother following delivery and alpha-interferon therapy was associated with a transient biochemical response.