To analyze the clinical and pathologic features of biopsy-proven pulmonary hamartomas at a tertiary referral center.We retrospectively reviewed institutional data on pulmonary hamartomas for a 17-year study period.The Mayo Clinic computerized medical records database was searched for patients who had biopsy, excision, or autopsy diagnosis of pulmonary hamartomas from 1976 through 1992. Medical records and all available histologic sections were reviewed.Of the 215 patients with histologically confirmed pulmonary hamartoma, 141 were men and 74 were women (approximately a 2:1 ratio). Two hundred eight patients were asymptomatic, 54 of whom were undergoing assessment for a comorbid disease process. Only four patients had new onset of respiratory symptoms. The peak incidence of occurrence was in the seventh decade of life. The mean size of the hamartomas were 1.5 cm (range, 0.2 to 6.0); no lobe was predominantly involved. Most hamartomas were resected by simple or wedge excision. Sixty-three patients (29.3%) had a concurrent neoplasm (most commonly, lung carcinoma). Follow-up ranged from 2 to 192 months (mean, 61). Eight postoperative deaths occurred. No recurrent pulmonary hamartomas developed. In one patient, lung carcinoma developed 33 months after excision of a hamartoma. In a second patient, sputum cytologic findings were abnormal 9 years later. A third patient had biopsy-proven adenocarcinoma metastatic to bone and an indeterminate lung nodule 2 years after resection of a pulmonary hamartoma.Pulmonary hamartomas are benign lung neoplasms that, in our referral population occurred most commonly in asymptomatic older men. A substantial number of our patients had concurrent neoplasms; however, many had been referred for cancer treatment. We found no evidence of either a malignant transformation or an unexplained association with other lung neoplasms.