While glucocorticoids remain the standard first-line treatment for chronic idiopathic eosinophilic pneumonia (CIEP), the long-term use is marred by significant side effects. This case study explores the effectiveness of mepolizumab, an anti-interleukin‑5 (IL-5) monoclonal antibody, as anovel corticosteroid-free alternative in treating CIEP. A50-year-old woman presented with a3-week history of progressive shortness of breath, dry cough and night sweats. The blood tests showed eosinophilia, and chest radiography identified lung consolidations. The CIEP was confirmed, ruling out other conditions through adetailed clinical and bronchoscopic work-up. The patient declined to be treated with systemic glucocorticoids. Treatment with mepolizumab was remarkable for effectively resolving symptoms and improving radiological findings without any prior or concurrent glucocorticoid therapy. Notably, the patient remained relapse-free over a2-year follow-up, underscoring mepolizumab's efficacy as acorticosteroid-free treatment for CIEP. This case study calls for further research into anti-IL‑5 treatment of rare respiratory conditions.