en Pediatric Pediatric Original Research Original Research In this study the clinical and epidemiological characteristics of congenital adrenal hyperplasia were evaluated prospectively in 47 patients admitted in Imam Reza Hospital in Mashhad during a 4 year period. 21-hydroxylase deficiency was present in 42 patients (89.3%), the simple virilizing form in 6 and the salt-losing form in 36 of them. 11b hydroxylase deficiency was present in 5 patients (10.7%). The median chronological age at diagnosis in the salt-losing form was 68 and 47 days in boys and girls respectively. 7 girls were considered to be male before the diagnosis was established. Parental consanguinity rate among families of patients was higher than the general population in Mashhad (82% vs. 35%). In 16.2% of patients the history of disease was positive in siblings. This study showed that the incidence of congenital adrenal hyperplasia is expected to be high due to a high rate of consanguinity in our population, hence genetic counseling before marriage would definitely be beneficial in our population. Congenital adrenal hyperplasia, Iran, Parental consanguinity. 75 78 http://mjiri.iums.ac.ir/browse.php?a_code=A-10-298-212&slc_lang=en&sid=1 R VAKILI 20031947532846003996 20031947532846003996 Yes From the Pediatric Endocrinology Ward, Imam Reza Hospital, Mashhad University of Medical Sciences,Mashhad, I.R. Iran.