The treatment of early-stage lung cancer or solitary-/oligo-metastatic thoracic malignancy includes minimally invasive thoracic surgical resection (MITS) or stereotactic body radiotherapy (SBRT). These treatments are delivered with curative intent and aim to minimize effects on the surrounding tissues. Technologic advances have enhanced the precision of these interventions; however, with these advances have come new challenges in particular the challenge of target localization to deliver therapy. Attempts to overcome this challenge have centered on the placement of fiducial markers (FM) to act as visible surrogates of tumor location. FM can provide accurate localization and tracking of tumors, even when the tumor is difficult to see on fluoroscopy or CT scan in the case of SBRT and/or when there is a loss of tactile feedback during MITS. A variety of FM are currently available for use. Some basic guidelines to follow when implanting FM for SBRT include the following: 3–6 should be implanted to so that three remain in place, they should be placed in and around the tumor at a distance of at least 2–5 cm from each other and such that the bulk of the tumor is bracketed by the fiducials, those placed outside the tumor should be placed as close to the edge of the tumor as possible, and they should not be placed collinearly. When placing FM for MITS, preoperative discussion with the surgical team is important if the markers are to be implanted by a separate team. In addition, the marker(s) should be placed such that they are visible from the visceral pleura and should include the whole of the target volume to ensure complete resection without margin involvement of tumor.