A left lower lobe of the lung was transplanted from a mother to her child, who had previously received a maternal bone marrow transplant for an immune defect. Following the bone marrow transplantation, the child had developed severe pulmonary fibrosis. Surgery and the early postoperative course have been uncomplicated. Immunosuppression with corticosteroids was administered for a short period, after which all immunosuppressive treatment was discontinued. The operation and the outcome are described both in the donor and recipient. Rehabilitation was slow, but one year later the patient is doing well.