Eosinophil-derived neurotoxin（EDN）is an intracellular protein released during eosinophil activation，possessing ribonuclease activity.As a pivotal immunoregulatory molecule，EDN exerts significant influence on the immune response of the organism.Serving as a biomarker，it can reflect the activation state of eosinophils，providing robust support for the diagnosis and dynamic monitoring of allergic diseases.This article focuses on the application of EDN in various allergic diseases，including its effectiveness as a diagnostic tool，assessment of disease severity，and prognosis.By reviewing existing research findings，this review aims to provide references for further research and clinical practice in related fields.