Most solitary pulmonary nodules are detected by chance on routine chest radiography in asymptomatic individuals. Diagnostic evaluation is necessary unless the nodule's size and shape has remained unchanged for at least 2 years, as documented on earlier x-rays. Radiographic techniques alone are insufficient in evaluating the nodule's malignity. For this purpose invasive diagnostic procedures (transthoracic biopsy, bronchoscopy) are mandatory. If these fail to establish a definite diagnosis, thoracotomy may be performed.