Sixty-five patients, aged 15 to 65 years, including 48 men (73.8%), were operated on for pulmonary (60) or endobronchial (5) hamartoma: there were 36 enucleations, 17 lobectomies (1 sleeve resection), 7 wedge resections, 4 segmentectomies, and 1 pneumonectomy. The average tumor diameter was between 2 and 4 cm; 15 were calcified. All were benign. Two were parts of an incomplete Carney's triad. Eight were associated with carcinomas, and three of these were bronchial carcinomas. Concerning these latter three tumors, a study of the incidence tables for northern France and of the standardized mortality ratio showed that the risk of bronchial cancer developing in patients with hamartoma, after a sufficient follow-up (61 patients), was multiplied by 6.66, and the chi 2 test showed a significant difference of incidence compared with that in the general population (p < 0.001). It is concluded that patients with hamartoma should be submitted to a complete evaluation and to a regular follow-up.