In living-donor lobar lung transplantation, the importance of donor safety should be emphasized because of the necessity of placing two donors at risk for each recipient. Approximately 3% of donors were reportedly readmitted to hospitals owing to complications after the donor surgery. Herein, we report two cases of living lobar lung transplant donors who exhibited accumulation of pleural effusion after discharge and were readmitted for treatment. The mechanism of this complication was not clearly elucidated, but surgeons should not ignore the possibility of pleural effusion necessitating readmission in living-donor lobar lung transplant donors.