We report the case of an adult patient with idiopathic pneumonia syndrome following allogeneic hematopoietic stem cell transplantation, which was successfully managed with venovenous extracorporeal membrane oxygenation (ECMO) and immunosuppressive therapy. A 30-year-old man with precursor B cell acute lymphocytic leukemia had received chemotherapy 10 years previously, with complete remission. He underwent allogeneic hematopoietic stem cell transplantation 4 months prior to enrollment, owing to leukemia relapse. One hundred thirty days post-transplant the patient developed shortness of breath, nonproductive cough, and low-grade fever for 1 week. He subsequently developed acute hypercapnic and hypoxic respiratory failure that was unresponsive to conventional medical therapy. He was successfully managed with venovenous ECMO for 19 days, with complete resolution of his respiratory symptoms. Thus, judicious use of ECMO as a bridge before steroid and other conventional therapy take effect in patients with isolated respiratory failure appears justified.