Rationale The objective of these studies was to assess the impact of the Jeffrey Modell Foundation's Physician Education and Public Awareness Campaign (PEPAC) on early diagnosis and management of Primary Immunodeficiencies (PI), and to make available an overview of the data provided by physician experts from the Jeffrey Modell Centers Network (JMCN) of Diagnostic, Research, and Referral Centers worldwide. The Network includes over 304 expert physicians at 138 academic teaching hospitals and medical schools in 39 countries and 120 cities, spanning 6 continents. Methods A survey was sent to the director of each center to ask how many patients were referred, diagnosed, followed, and treated at the centers. Each center was also asked to provide a list of the specific PI defects seen among their patients. Results (i) The PEPAC generated substantial increases in diagnosis, referrals, and treatment of patients with PI disease. (ii) The number of diagnostic tests performed by participating physicians at Jeffrey Modell Centers increased annually by nearly 5 times over a 4 year period. (iii) The number of patients reported with a suspected PI disease totaled 37,544 and 30,283 of these patients were identified with specific PI defects. (iv) The data was sorted and reported in the order of the 43 major PI diseases, and classified by the 8 major PI groups. The data was further organized by the 9 major geographic regions participating and the 15 leading defects by region. (v) The JMCN reports were compared to the European Society for Immunodeficiencies (ESID) registry and there was little difference in the respective percentages for the major immunodeficiency groups. Conclusions These studies provide insight on the number of patients followed, diagnosed, and treated at Jeffrey Modell Centers around the world, the specific PI defect of 30,283 patients, where they were diagnosed and treated, who diagnosed and treated them, and what type of treatment that they are receiving.