OBJECTIVE: The purpose of this study is to evaluate the feasibility and effectiveness of a nonradioactive magnetic marker wireless localization technique. MATERIALS AND METHODS: A retrospective review was performed of consecutive patients who underwent image-guided needle localization with nonradioactive magnetic markers and subsequent surgical excision from March to August 2017. Indications for marker placement, lesion type, imaging guidance used for marker placement, postprocedure mammographic imaging and reports, surgical reports, and surgical margin status were reviewed. RESULTS: A total of 188 patients (mean age, 59 years; range, 22-89 years) underwent image-guided localization with 213 magnetic markers and subsequent surgical excision. The indications for marker placement included invasive carcinoma (96 markers [45.1%]), ductal carcinoma in situ (41 markers [19.2%]), and high-risk lesions (71 markers [33.3%]). Localization markers were most commonly placed for masses (96 markers [45.1%]) and were deployed under mammographic guidance (160 markers [75.1%]) or sonographic guidance (53 markers [24.9%]). Technical success, which was defined as placement of the magnetic marker within 1 cm of the target, was achieved for 206 of 213 markers (96.7%). All 213 markers were successfully retrieved at surgery. Of 137 cases of in situ or invasive carcinoma, 30 (21.9%) had tumor-positive or close surgical margins that required reexcision. No major or minor complications were observed during marker placement, intraoperatively, or postoperatively. CONCLUSION: Image-guided needle localization with magnetic markers is a safe, feasible, and effective method for localizing breast lesions. Magnetic marker localization has the potential to replace conventional wire needle localization and radioactive seed needle localization for lesions that require surgical excision.