We report a long-term outcome of extremely oversized lung allograft. A left lower lobe transplantation from an adult donor was performed on a four-year-old recipient after left pneumonectomy. Lobar lung allograft volume was calculated to be approximately 180% of the recipient's predicted left thoracic capacity. Accordingly, the lung allograft was compressed to 47% of its original size immediately after transplantation. Initial postoperative functional recovery of the allograft was excellent despite this severe compression. As the patient grew physically, both his forced expiratory volume in 1 s (FEV(1)) and his left lung volume increased slowly but steadily during an observation period of two years and four months after transplantation.