Background: Atopic dermatitis (AD) is a chronic inflammatory skin disease, characterized by intense itch, typical localization and a specific image of skin lesions. Pathogenesis of pruritus in AD is not fully understood, but recent studies emphasize the role of interleukin-31 (IL-31). This relatively recently described cytokine is considered to be a potential mediator inducing pruritus in AD. Aim of the Work: was to assess the correlation of serum IL-31 level and the disease severity in children with AD. Patients and Methods: a case control study. Sera were obtained from 50 AD children and 30 healthy volunteers. IL-31 levels were measured using ELISA with standard kits from EIAab R&D Systems. Serum IL-31 levels were correlated with AD disease activity. Disease severity in children with AD was assessed using the SCORAD (Severity scoringof atopic dermatitis) index. Results: Serum IL-31 level was significantly higher in AD children (Mean ± SD 99.73 ± 75.93) than in healthy children (Mean ± SD 54.01 ± 57.36), (p-value = 0.019). Serum IL-31 levels correlated positively with the calculated severity score (SCORAD index), (rs = 0.480, p- value <0.001) Conclusion: The results of this study confirm the importance of IL-31 in AD pathophysiology. Serum IL-31 level is an objective reliable marker of AD severity in children. It may represent a novel target for antipruritic drug development.