TNFRSF13B/TACI defects have recently been associated with common variable immunodeficiency (CVID) pathogenesis. Considering that TNFRSF13B/TACI is very polymorphic and the frequency of its alterations may be different in various ethnic groups, we analyzed their prevalence in 47 Greek patients with antibody deficiencies, including CVID (16 patients), IgAD (16 patients), selective IgG4D (11 patients), and transient hypogammaglobulinemia of infancy (4 patients). A rather high frequency of TNFRSF13B/TACI defects was identified in patients with selective IgG4D (18.18%). Moreover, a patient with CVID was heterozygous in the common C104R mutation (6.25%). Both his children and a further healthy individual carried the same mutation, albeit without recurrent infections and/or hypogammaglobulinemia. The common polymorphisms V220A and P251L were identified in all disease subgroups, in an almost similar frequency with that observed in 259 healthy controls. Our data provide further evidence that TNFRSF13B/TACI alterations are not causative of CVID. Possibly, they predispose to humoral deficiencies and/or contribute to their phenotype when combined with other immune gene alterations.