Bronchiolitis obliterans (BO) is a potentially life-threatening complication following allogeneic stem cell transplantation (SCT) and usually carries a poor prognosis. Immunosuppressive medications are the main treatment, but are rarely effective, especially when the disease is severe. Thus, both early detection and alternative therapeutic approaches of post SCT BO are needed. We report our experience with Budesonide/Formoterol, an inhaled steroid and long-acting bronchodilatator combination, in a group of patients with mild to moderately severe BO after SCT whose systemic immunosuppressive treatment had not been modified. Thirteen patients were treated. The diagnosis of BO was based on the presence of respiratory symptoms and air-trapping on expiratory lung high-resolution computed tomography in all patients, associated with irreversible airflow obstruction in seven cases. The median follow-up was 12.8 months (range: 5-29 months). All patients improved clinically, and both forced expiratory volume in 1 (FEV(1)) and mean expiratory flow values increased significantly during follow-up (534+/-268 ml in absolute values and 36+/-27% compared to pretreatment values for FEV(1); P<0.02). These encouraging results provide new insights in the therapeutic approach of BO after SCT and require confirmation in a larger group of patients with a longer follow-up.