RÉSUMÉ
This study was designed to assess the relationship between the serum level of 25-hydroxyvitamin D and the clinical, functional severity and the level of asthma control among Egyptian asthmatic children. This case-control cross-sectional study was conducted on 50 asthmatic patients from those regularly attending the Pediatric Chest Clinic, Children's Hospital, Ain Shams University. Twenty healthy children of matched age and sex were recruited as the control group. Pulmonary function tests were significantly decreased in the asthmatic cases compared with the control [P < 0.01]. The serum vitamin D level was found to be significantly decreased in asthmatic children compared with the control group [P < 0.001]. Out of the 50 asthmatic children, 20 had a serum vitamin D level of less than 25 ng/ml, and were considered to be 'vitamin D deficient', whereas the remaining 30 children had a level ranging between >25 ng/ml and