Background: There is no doubt that unique immunological changes occur during pregnancy but its impact on virology and biochemical makers of hepatitis B infection is not well understood. Rapid changes in the immunological profile postpartum and consequent rebound of the inflammatory response result in hepatic flares. Treatment with antiviral drugs in pregnancy and beyond has been said to reduce the associated morbidity and mortality due to this flare. A cursor search through the literature revealed no local study on liver dysfunction in pregnant women with hepatitis B virus infection. Objective: To determine whether there is increase in liver dysfunction in pregnant women infected with hepatitis B virus in Lagos Island Maternity Hospital using the rise in serum alanine aminotransferase as a determinant of liver dysfunction. Method: The study was a comparative study involving 110 pregnant women with hepatitis B virus in Lagos Island Maternity Hospital as study group and equal number of pregnant women that were not infected with hepatitis B virus as controls. The difference in serum ALT between the two samples that were collected at booking and on day 2 postpartum was compared between the study and control groups and among the various subgroups in the study group based on results of hepatitis B envelop antigen(HBeAg),anti HBc, IgM anti-HBc and anti- HBS serological tests.