The most prevalent form of primary immunodeficiency with a total defect of antibody production in adults is common variable immunodeficiency (CVID). Compared to other forms of primary immunodeficiency, CVID is characterized by later onset of clinical manifestations represented by infectious, autoimmune and malignant diseases. To avoid development of complications and patient incapacitation, it is necessary to make an early diagnosis and initiate regular replacement therapy with intravenous immunoglobulins.