Common variable immunodeficiency is the most commonly seen primary immune deficiency condition in adults, characterized by impaired B cell differentiation. The patient is diagnosed with common variable immunodeficiency by recurrent bacterial infections usually accompanied by chronic lung diseases, gastrointestinal/liver diseases, granulomatous diseases, autoimmunity, lymphoid hyperplasia, splenomegaly or malignancies. Serum IgG concentration is significantly low along with low IgA and/or IgM concentrations. Intravenous immunoglobulin (IVIG) is the first choice of treatment. Immunoglobulin treatment ameliorates recurrent infections and associated complications such as autoimmune diseases and pulmonary injury. The main cause of death in patients with common variable immunodeficiency is chronic lung diseases or malignancies, because acute bacterial infections is usually prevented by IVIG therapy.