Summary. Primary immunodeficiency disorders include a variety of diseases that render patients more susceptible to infections. To determine the percentage of different primary immunodeficiency disorders diagnosed in the Children’s Medical Center Hospital affiliated to Tehran University of Medical Sciences in Iran, we retrospectively reviewed the charts of the patients being referred to our hospital for immunologic evaluation of recurrent infections during a 20 year period. Among these patients, antibody deficiencies were the most frequent ones and were found in 52.6% of patients (n=130). T-cell disorders, phagocytic disorders and complement deficiencies were found to
be present in 24.69% (n=61), 22.2% (n=55) and 0.4% (n=1) respectively. On the whole, common variable immunodeficiency was the most frequent disorder (n=65), followed by ataxia telangiectasia (n=39), X-linked agammaglobulinemia (n=33), chronic granulomatous disease (n=29) and selective IgA deficiency (n=20). This study reveals that antibody deficiencies are the most common type of disorders as shown in other studies. A comparative study shows some differences between our results and other registries. This article also indicates that immunodeficiency disorders should be considered in patients with recurrent infections.

Key words: Primary immunodeficiency disorders; Infection; Frequency; Iran.