The solitary pulmonary nodule (SPN) has always been a diagnostic challenge for the radiologists. Currently, with increased utilization of computed tomography (CT) greater number of nodules is being discovered, with numerous indeterminate lesions, which frequently cannot be immediately classified into benign or malignant category. In this article we review the imaging features of benign and malignant round opacities; we demonstrate currently used standards and also more advanced techniques that are helpful in evaluating SPNs such as contrast-enhanced CT, PET/CT imaging and also pathologic sampling with biopsy or surgical resection. We also summarize the methods of evaluating and managing SPNs based on the latest guidelines from the Fleischner Society and American College of Chest Physicians.