Tehran University of Medical Sciences Iranian Journal of Allergy, Asthma and Immunology 1735-1502 11 2 2012 06 15 89 109 EN Asghar Aghamohammadi Research Center for Immunodeficiencies, Pediatrics Center of Excellence, Children's Medical Center, Tehran University of Medical Sciences, Tehran, Iran Hassan Abolhassani Research Center for Immunodeficiencies, Pediatrics Center of Excellence, Children's Medical Center, Tehran University of Medical Sciences, Tehran, Iran Payam Mohammadinejad Research Center for Immunodeficiencies, Pediatrics Center of Excellence, Children's Medical Center, Tehran University of Medical Sciences, Tehran, Iran Nima Rezaei Research Center for Immunodeficiencies, Pediatrics Center of Excellence, Children's Medical Center, Tehran University of Medical Sciences, Tehran, Iran AND Molecular Immunology Research Center, Department of Immunology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran 2015 10 01 Recurrent and chronic infections in children are one of the most common reasons for physicians' visits that make a diagnostic challenge to pediatricians. Although the majority of referred  children  with  recurrent  infections  are  normal,  underlying causes  of  recurrent infection  such  as  atopy,  anatomical and  functional  defects,  and  primary or  secondary immunodeficiency must be considered in evaluation of children with this complaint. Although primary immunodeficiency diseases (PIDs) were originally felt to be rare, it has became clear that  they are much  more  common  than  routinely appreciated. Early and accurate detection  of  PIDs  in children is essential to  institute  early lifesaving care and optimized treatments. Therefore in the approach to children with recurrent infections, careful medical history taking and physical examination with more attention to warning PIDs signs and symptoms are essential to distinguish those children with underlying PIDs from those who are normal or having other underlying disorders. If indicated, appropriate laboratory studies including simple screening and advanced tests must be performed. https://ijaai.tums.ac.ir/index.php/ijaai/article/view/335 https://ijaai.tums.ac.ir/index.php/ijaai/article/download/335/335