Acute pulmonary dysfunction remains a frequent and severe complication of hematopoietic stem cell transplantation (SCT). Almost half of the pulmonary insults that occur in this seating are noninfectious in origin and are referred to as idiopathic pneumonia syndrome (IPS). In this series of 3 patients, etanercept (Enbrel; Immunex, Seattle, WA), a soluble, dimeric tumor necrosis factor alpha-binding protein, was administered to 3 consecutive pediatric allogeneic BMT recipients with IPS. The administration of etanercept, in combination with standard immunosuppressive therapy, was well tolerated and associated with significant improvements in pulmonary dysfunction within the first week of therapy. These data suggest that etanercept may represent a safe, non-cross-reactive, therapeutic option for patients with IPS and that clinical trials studying etanercept for this indication are warranted.