Improvements in immunosuppression and surgical techniques have made unilateral lung transplantation feasible in selected patients with end-stage interstitial lung disease. We report two cases of successful unilateral lung transplantation for end-stage respiratory failure due to pulmonary fibrosis. The patients, both oxygen-dependent, had progressive disease refractory to all treatment, with an anticipated life expectancy of less than one year on the basis of the rate of progression of the disease. Both patients were discharged six weeks after transplantation and returned to normal life. They are alive and well at 26 months and 14 months after the procedure. Pulmonary-function studies have shown substantial improvement in their lung volumes and diffusing capacities. For both patients, arterial oxygen tension is now normal and there is no arterial oxygen desaturation with exercise. This experience shows that unilateral lung transplantation, for selected patients with end-stage interstitial lung disease, provides a good functional result. Moreover, it avoids the necessity for cardiac transplantation, as required by the combined heart-lung procedure, and permits the use of the donor heart for another recipient.