Background: Atopic Dermatitis (AD) is an allergic inflammatory skin disease with significant cost and morbidity to the patients and their families. Vitamin D has been suggested to have a role in the pathogenesis of allergic disorders, including AD. Objective: The aim of the study was to measure the serum levels of vitamin D in the form of 25-hydroxy vitamin D in children with AD and to correlate them with the severity of the disease. Patients and methods: The study included forty children with the clinical diagnosis of AD. Using Scoring Atopic Dermatitis (SCORAD) index, the patients were divided into three groups; mild (SCORAD index<25), moderate (25-50) and severe (>50). Vitamin D levels were measured in the sera of the patients using Chemiluminescent method. Specific IgE to Staphylococcus aureus (S.aureus) Enterotoxins (A, B and C) and Malessazia furfur (M.furfur) in the sera of the patients was also measured using Immunocap system. Results: AD was mild in 16 patients, moderate in 14 patients and severe in 10 patients. The mean SCORAD index ±SD was 14.01±5.6, 38.71±7.8 and 60.8±7.5 in the three groups respectively. Mean vitamin D levels ±SD in the sera of the patients in ng ml-1 were sufficient (36.3±13.06) in 15 patients, insufficient (26.6±7.4) in 16 patients and deficient (19.8±5.2) in 9 patients. There was a significant inverse correlation between the serum levels of vitamin D and the severity of AD (r=-0.48, P=0.003). There was also a significant difference between the mean serum level of vitamin D in mild and moderate AD (P<0.05), and mild and severe AD (P<0.05). Specific IgE to S.aureus enterotoxin and to M.furfur antigens was more in patients with severe AD who had deficient levels of vitamin D than in those with mild or moderate disease. Conclusion: Vitamin D level is inversely related to the severity of the disease in AD patients and consequently it may have a role in its treatment.