The increasingly early diagnosis of breast disease and the more widespread use of primary systemic therapy leads to an increasing number of surgeries for non-palpable breast lesions (NPL) in clinical practice. Breast-conserving surgery often requires the use of an image-guided preoperative localization procedure, in which a device is placed within the lesion to be removed to guide the surgeon during surgery. These are patients with small, non-palpable tumors detected in the population screening mammogram, cases with significant reduction of the lesion after neoadjuvant chemotherapy and sometimes it is even necessary to mark axillary lymphadenopathies prior to systemic treatment. For decades, wire localization has been the standard for preoperative marking in breast cancer. Due to the external component of this device, extreme care must be taken not to alter its position before surgery, which is why it is placed hours before surgery and entails complex and limited flexibility in surgical programming. Intraoperative ultrasound improves this drawback but has the limitation that it can only be performed in those NPLs that have ultrasound translation. The Radioguided Occult Lesion Localization (ROLL) technique, although it is another alternative adopted by many institutions, is not without complications, among which the possibility of diffusion of the radiotracer into healthy tissue stands out. To overcome these problems, more recently, 125I radioactive seeds began to be used. Subsequently, thanks to technological advances, non-radioactive seed alternatives such as radar reflectors, magnetic seeds and radio frequency markers have emerged. These locating devices can be placed days before surgery, avoiding wire-related problems and complications. They are introduced percutaneously and identified intraoperatively using a detector device. There is no perfect intraoperative localization method for NPL excision, but fortunately, we have multiple techniques with different advantages and disadvantages that must be assessed and adapted to the center's own resources, the type of surgery, and always to the benefit of the patient.Copyright © 2021 Sociedad Española de Medicina Nuclear e Imagen Molecular. Published by Elsevier España, S.L.U. All rights reserved.