Abstract Background: Eosinophils are encounterd in many skin disease but the role of eosinophils in atopic dermatitis (AD) remains uncertain. Objective: We aimed to examine the role of serum eosinophil derived neurotoxin (EDN), eosinophil cationic protein (ECP) and total immunoglobulin (Ig) E as a bio-marker of disease severity and relapse in severe recalcitrant AD. Methods: We enrolled 99 patients with AD: 37 with severe recalcitrant AD, with severe AD and 42 with mild/moderate AD. We examined the difference in difference in serum level of total IgE, ECP and EDN between the groups and whether any correlation existed between disease severity and ECP or EDN. Lastly, defference in levels of ECP or EDN between those who experienced relapse was examined in the severe recalcitrant group. Results: Serum levels of total IgE, ECP and EDN were significantly higher in the severity recalcitrant AD group and severe AD group in comparison with mild/moderate AD group. There was no significant difference in serum levels of total IgE, ECP and EDN between severe recalcitrant group and severe group. EDN showed a significant posotive correlation with SCORAD. There was no significant correlation between EDN and ECP. In the severe recalcitrant group, 29.7% of patients experienced relapse and EDN was significantly higher in those who experienced relapse. The cutoff value of EDN for predicting relapse was 64.5. Conclusion: EDN correlated with disease severity AD. EDN may predict relapse in severe recalcitrant AD. Serum level of EDN could be considered as a candicate molecule as a clinical biomarker for evaluating AD disease activity as well as predictor for relapse.