Purpose The optimal immune globulin replacement dosages required over time to minimize infection risks in patients with Primary Antibody Deficiencies are not definitely established. As with many interventions, there may be specific subgroups of patients who are more likely to benefit from treatment with higher or lower dosages. The aim of the study was to verify the efficacy of a rationale for individualized immune globulin utilization and to elucidate the effects of care on patient outcome. Methods Single centre interventional study on 108 patients with Primary Antibody Deficiencies. The objective was to determine for each patient the best interval between immune globulins administration in order to: • Keep IgG trough levels >500 mg/dL, • Minimize of major infections (pneumonias and infections requiring hospitalization), • Minimize of adverse events (AE). Results Ninthly eight per cent of patients achieved the objective of the study. Patients who had low switched memory B cells and low IgA serum levels and/or are affected by bronchiectasis and/or enteropathy and/or continued to experience adverse events despite pre-medications, achieved the study objective by shortening the administration intervals to 2-weeks or to 1-week without the need to increase the monthly cumulative immunoglobulin dosage and its relative cost. The adverse events were reduced by administrating low Ig dosages in a single setting. Patients without risk factors achieved the study objective with immune globulin replacement administered with the widely used interval of 3 or 4 weeks. Conclusions The exact timing and optimal immunoglobulin prophylaxis regimen might be tailored according to clinical and immunological markers. © 2014 The Author(s).