Surgeons are increasingly required to resect nonpalpable breast lesions only detected by mammography. Methods for preoperative localization of such lesions were reviewed with emphasis on invasive radiologic techniques using injection, needle, and wire markers. Invasive localization of nonpalpable breast lesions is a relatively simple procedure that should be available wherever breast biopsies and mammography are performed. Its precision and success relate to the radiologist's experience in marker placement and to close cooperation between the radiologist and surgeon.