The solitary pulmonary nodule is a common radiologic abnormality that is often detected incidentally. Many malignant and benign diseases can present as a solitary pulmonary nodule on a chest roentgenogram. It is important to differentiate malignant nodules from benign nodules in the least invasive way and to make as specific and an accurate diagnosis as possible. In this paper, a diagnostic approach to the solitary pulmonary nodule was discussed.