The 2013 Immune Deficiency Foundation (IDF) National Treatment Survey is the fourth such survey conducted by IDF. Others in this series were conducted in 1997, 2003 and in 2008. This study examines, in detail and focus, the patient experiences with Ig therapy. Data from this survey helps quantify the impact Ig therapy has on patient health outcomes, and the issues and challenges patients may face while on Ig therapy, and it helps further define the characteristics of patients who receive Ig therapy for their PI.