PurposeRadiosurgery requires precise lesion localization. Fiducial markers enable lesion tracking, but complications from insertion may occur. The purpose of this study was to describe complications of fiducial marker insertion into pulmonary lesions.Materials and methodsClinical and imaging records of 28 consecutive patients with 32 lung nodules or masses who underwent insertion of a total of 59 fiducial markers before radiosurgery were retrospectively reviewed.ResultsEighteen patients (67%) developed a pneumothorax, and six patients (22%) required a chest tube. The rates of pneumothorax were 82% and 40%, respectively, when 18-gauge and 19-gauge needles were used for marker insertion (P = 0.01). Increased rate of pneumothorax was also associated with targeting smaller lesions (P = 0.03) and tumors not in contact with the pleural surface (P = 0.04). A total of 11 fiducials (19%) migrated after insertion into the pleural space (10 markers) or into the airway (1 marker). Migration was associated with shorter distances from pleura to the marker deposition site (P = 0.04) and with fiducial placement outside of the target lesion (P = 0.03).ConclusionFiducial marker placement into lung lesions is associated with a high risk of pneumothorax and a risk of fiducial migration