Cytomegalovirus is a double stranded DNA virus that can be present in nearly all organs and body fluids. The primary infection is usually asymptomatic in the immunocompetent host and it is common among adolescents and young adults. The symptomatic form appears, in the majority of cases, as a mononucleosis syndrome with full recovery without specific treatment. We report a case of a 25 years old woman who presented with hepatitis due to CMV infection and history of omalizumab administration one month earlier. This recombinant monoclonal antibody is used to control refractory asthma and chronic spontaneous urticarial as it inhibits human IgE. Despite that, the long course of the disease lead us to initiate treatment with valganciclovir. The improvement after that was rapid and complete.