IVIG (Intravenous immunoglobulin) have significantly improved the prognosis and the quality of life of immunodeficient patients and are routinely used as substitutive therapy. Transient hypogammaglobulinemia of infancy (THI) is a primary humoral immunodeficiency characterized by a transient IgG defect, but is not considered as a disease that justifies substitutive treatment and thus the use of IVIG as an alternative to antibiotic prophylaxis remains controversial also in symptomatic children. We treated 13 THI children severely symptomatic with IVIG (400mg/kg/every 3 weeks ) for a limited period (2 or 3 months) and followed them for 1 to 3 years. During the follow-up, the frequency of overall infections decreased approximately tenfold (from 0.39 to 0.047 infection/month per child) and no severe infections were reported. Although this study lacks untreated controls, the results suggest that the observed clinical improvement is correlated to IVIG therapy. Furthermore, our study suggests that the infused IVIG have no long-term effect on endogenous IgG production and do not lengthen the immunodeficiency condition since all children produced a normal amount of specific IgG in response to vaccination carried out 5 months after the end of infusions. In conclusion, our results suggest that IVIG may stop the vicious circle of infection-immunodeficiency and should be considered as a first line therapy in highly symptomatic THI children.