In this study, we compared intravenous immunoglobulins (IVIG) and subcutaneous immunoglobulins (SCIG) in terms of serum IgG concentration and incidence of infections in patients with hypogammaglobulinemia secondary to chemo-immunotherapy regimens including the anti-CD20 monoclonal antibody rituximab. Fourteen patients with a B-cell lymphoproliferative disease treated for at least six months with a rituximab-including chemo-immunotherapy regimen were recruited. Mean serum levels of IgG were higher during replacement therapy than at the end of rituximab treatment (p<0.001). Moreover, serum IgG level was higher during replacement therapy with SCIG than with IVIG (p<0.001). No differences in the incidence of infections were observed. Although the non-randomized design and the small number of patients do not allow definitive conclusions to be drawn, study results suggest that higher mean serum IgG levels are reached when using the subcutaneous route after a switch from the intravenous regimen, and that IVIG and SCIG offer comparable protection against infections.