Common Variable Immunodeficiency (CVID) comprises a heterogeneous group of primary antibody deficiencies which lead to a range of complications, including infectious, neoplastic and inflammatory disorders. This report describes monozygotic twin brothers with CVID who developed cryptogenic liver disease and subsequently hepatopulmonary syndrome (HPS). This is the second report of the association of HPS and CVID. Its occurrence in two identical twins implicates a genetic basis.