We evaluated the incidence, the risk factors, and the outcome of late-onset noninfectious pulmonary complications (LONIPCs) among 50 patients who underwent allogeneic stem cell transplantation from unrelated donors. Of the 39 patients surviving at least 3 months, 10 (26%) fulfilled the diagnostic criteria of LONIPCs and were further subclassified as having bronchiolitis obliterans (four patients), bronchiolitis obliterans with organizing pneumonia (four patients), and interstitial pneumonia (two patients). Two patients had a durable partial remission after treatment with prednisone and cyclosporine; the remaining eight patients did not respond to treatment and five of them died of respiratory failure. Advanced stage of disease at transplant and chronic extensive graft-versus-host disease (GVHD) were significantly associated with the development of LONIPCs. Pulmonary function test (PFT) results before transplantation were similar in all patients, but patients with LONIPCs had a significant decrease in PFT indexes at the third month after BMT compared with controls. Moreover, the rate of cyclosporine taper during the fourth and fifth months after BMT was significantly more rapid in patients with LONIPCs than in controls, suggesting that the risk of LONIPCs may be influenced by a faster reduction of GVHD prophylaxis.