Living-donor lobar lung transplantation is an alternative to conventional cadaveric lung transplantation for both pediatric and adult patients. In 16 patients, postoperative immunosuppression included cyclosporine, azathioprine, and corticosteroids. Cyclosporine delivery began during the first few postoperative hours via a nasal feeding tube inserted to the proximal jejunum. The dosage was adjusted to maintain trough levels in the target range of 250 to 350 ng/dL during the first 3 months; however, it was often reduced when renal dysfunction was suspected. We judged acute rejection on the basis of radiographic and clinical findings without lung biopsy. During the first month, 15 of 16 patients experienced at least one episode of acute rejection with an average of 1.7 episodes/patient. Cyclosporine was switched to tacrolimus in four patients (25%) due to repeated episodes of acute rejection. No patients experienced infectious complications during the first months. All 16 patients are currently alive with a follow-up period of 3 to 59 months. Three patients (19%) have developed unilateral bronchiolitis obliterans. Cyclosporine-based immunosuppression can be safely given to the recipients of LDLLT without significant adverse effects but the incidence of acute rejection is relatively high. The optimal long-term immunosuppressive regimen remains to be established.