Despite preliminary evidence, the role of probiotic and synbiotic in treatment of the atopic dermatitis has shown varying results. We aimed to evaluate whether synbiotic supplementation decrease severity of atopic dermatitis (AD) in childhood. In a randomized double blind-placebo controlled trial, we evaluated the synbiotic supplementation efficiency on the treatment of atopic dermatitis. Infants aged 1-36 months with moderate to severe atopic dermatitis were randomized (n=41) and received either synbiotic (probiotic plus prebiotic) (n=20) or placebo (n=21) daily as a powder for two months. Emollient (Eucerin) and topical corticosteroid (Hydrocortisone) were permitted. Children were scored for severity of atopic dermatitis (SCORAD). Also allergen Skin Prick Tests (SPT), IgE blood level and eosinophil count were measured at first visit. Patients' SCORAD were reevaluated at the end of intervention. We followed 36 out of 41 subjects for two months (drop out rate = 9%). In the whole group, the mean Total SCORAD (at base line 40.93) decreased by 56% (p=0.00). The mean Objective SCORAD (at base line 31.29) decreased by 53% (p=0.00). There was no significant difference in the mean decrease of total SCORAD between placebo (22.3) and synbiotic groups (24.2). There was also no difference between two intervention groups in the mean decrease of total SCORAD regarding to different demographic, clinical and para clinical subgroups. This study could not confirm synbiotic as an effective treatment for childhood atopic dermatitis and further studies are needed. These findings challenge the role of synbiotics in the treatment of childhood atopic dermatitis.