Background Primary immunodeficiencies (PID) are a group of heterogeneous and relatively rare diseases. Aim to determine the clinical characteristics, outcome and genetic data of primary immunodeficiencies in pediatrics patients. Methods A retrospective, descriptive and multicentered study, enrolling 33 children presenting a PID in Tunis, during a period of 22 years (1991-2012). Resultats a masculine predominance has been noticed with a sex ratio at 2,3. Consanguinity was found in 71% of family cases. History of early infant deaths was found in 42% of cases. The media age of diagnosis was of 1 year 2 months. The median diagnosis delay was of 11 months and 1/2. Most frenquently observed PID were combined immunodeficiency (36%), mostly severe combined immunodeficiency (SCID) (21%), followed by congenial defects of phagocyte function (33%), mostly chronic granulomatosis disease (21%). Antibody defects were found in 21% of cases. Most frequently observed out comes were lung infections (66%) recurrent oral thrush (57%) and diarrhea (42%). Most important complications were severe infections and bronchiectasis. 30% of patients were dead by the end of the study. A molecular characterization was performed in 33% of patients, and an antenatal diagnosis was performed in 10% of cases. Conclusion The PID are a group of disease with variable expressions and etiologies. Their frequency remains understimated in Tunisia, and their management, difficult and insufficient. We suggest the establishment of systematic genetic consulting visit, the creation of a national registry and developing bone marrow transplantation in children in Tunisia.