This study evaluates the clinical/immunological features and outcomes of 91 patients with the diagnosis of transient hypogammaglobulinemia of infancy(THI). Mean age at diagnosis was 8.4±5.2 months. IgG levels normalized at 30.6±11.88 months. Sixty three patients (69.3%) resolved in their first 3 years of life and 28 patients (30.7%) thereafter. In the univariate analysis, presence of atopy, occurrence of recurrent infections (>6/year) and hospitalization, initial low IgA and IgM levels were found to be associated with the late recovery. Patients with longer breastfeeding duration recovered earlier. Recovery time for Ig levels was found to be longer in patients who received IVIG (n=55, 60.4%). This study confirmed that delayed resolution in THI is not rare. Frequent infections, initial low IgA and/or IgM levels and presence of atopy were found as associated factors for the late recovery. Breastfeeding should be encouraged and IVIG should be used in well selected patients.