Background. Cystic fibrosis is a congenital, progressive disease affecting many organs. It frequently leads to severe respiratory failure, which can be treated by means of a double lung transplantation. Single lung transplantation is justified only in certain cases. Case report. This is a case report describing a 20-year-old female patient who became the recipient of a single lung transplant as a result of cystic fibrosis. The transplant was performed during cardiothoracic surgery, which included an intervention in the right atrium. At the age of 14, the patient underwent left pneumonectomy. In addition, the patient had a percutaneous endoscopic gastrostomy placed and a vascular port implanted. During preoperative evaluation, she presented with clinical symptoms of chronic respiratory failure. The patient was approved for lung transplantation at the age of 16. After 2 years on the national lung transplant waiting list, in 2018, the patient underwent right lung transplantation and removal of numerous thrombi in the right atrium during 1 procedure. This surgery was accomplished with the use of extracorporeal circulation, which is an extracorporeal membrane oxygenator combined with cardiopulmonary bypass. The patient was discharged 3 weeks after the procedure in good general condition. Presently, her pulmonary function is excellent and she presents with normal respiratory capacity. Conclusions. Patients with cystic fibrosis often require double lung transplantation. Under normal circumstances, performing only a single lung transplantation would be considered medical malpractice. However, in certain cases, a single lung transplant is a life-saving procedure.