Pulmonary hamartoma is most common benign tumor of the lung and is not recognised as having a character of malignant transformation. So, longtime radiological observation is not uncommon for patients with diagnosis of pulmonary hamartoma from computed tomography (CT) finding. Although pulmonary hamartoma does not transform to malignancy, high frequency of coexistence hamartoma and lung cancer has been reported. We experienced 14 cases of resected pulmonary hamartoma, and 3 of them had lung cancer, showing that 21.4% of pulmonary hamartoma coexisted with lung cancer. Patients with pulmonary hamartoma should undergo sufficient evaluations for malignancy.