The feasibility and immediate tolerance of single-lung transplantation were recently demonstrated in patients with severe obstructive lung disease. Since initial reports, hundreds of procedures have been performed worldwide in such patients, but views regarding the results are still controversial. Since few data concerning medium-term functional results are available, we report here our series of 20 patients with chronic obstructive pulmonary disease who received a single-lung transplant. A group of 16 patients who survived for 6 mo or more form the basis of this report. Current 1- and 2-yr actuarial survival are 75 and 70%, respectively, with 4 perioperative deaths and 2 deaths at 9 and 15 mo after transplantation. Before transplantation the patients were severely obstructive, with a FEV1 of 17 +/- 6% of predicted, a PaO2 of 51 +/- 10 mm Hg, a PaCO2 of 49 +/- 11 mm Hg, and a 6 min walk test of 99 +/- 84 m. A significant functional improvement was observed postoperatively, the patients' FEV1 at 3 mo reached 53 +/- 13%, PaO2 81 +/- 3 mm Hg, and PaCO2 39 +/- 3 mm Hg. The distance covered during 6 min was 587 +/- 147 m at 6 mo. Throughout postoperative follow-up, lung function remained stable in some patients but decreased in others after several mo, this decline related to the occurrence of bronchiolitis obliterans, except in two patients who had airway complications. Impairment in lung function led to retransplantation in four patients, with good clinical results in three patients, one patient dying postoperatively.(ABSTRACT TRUNCATED AT 250 WORDS)