KEY WORDS: excisional breast biopsy/methods; hook-wire localization;isosulfan blue dyeLocalization of nonpalpable breast lesions is one of the major challenges in breast surgery. Calcifications and focal areas of dense glandular breast tissue appear white on mammograms, making it difficult to differentiate between cancerous lesions and other structural abnormalities. The goal is the earliest possible identification of in situ breast carcinoma, because until the past decade radical operations could offer a cure rate for such tumors of nearly 100% [1].In such cases, breast biopsy, especially using minimally invasive percutaneous methods, have gained recognition during recent years. Nevertheless, excisional biopsy still remains a proven method for the final diagnosis, particularly in health care settings in which the most recent technology is not available because of cost. The major problem is the precise localization of the lesion so that the amount of breast tissue excised can be minimized. This is particularly necessary, especially in young women with small breasts, to minimize the adverse esthetic effects of biopsy surgery.In cases in which breast lesions are nonpalpable, the problem of localization can be partially solved by inserting a hook-wire into the lesion under direct vision. The hook-wire is very thin and flexible, and the surgeon then blindly follows its course into the breast. Sometimes using this technique, however, large portions of surrounding tissue must be removed to ensure that the lesion is captured. In addition, accidental cutting of the hook-wire during dissection is not uncommon, as it is difficult to identify the terminal edge that is inserted into the lesion, with the potential danger of the terminal edge remaining in place after the procedure. To ensure complete excision of the lesion and the hook-wire integrity radiographic evaluation would then be necessary. If the lesion or the tip of the wire can not be found, the surgeon then must remove additional tissue in a repeat procedure.To increase the precise identification rate of nonpalpable lesions of the breast, before using the hook-wire localization technique, we also use an isosulfan blue dye technique, as described below. We believe that it helps us reduce the rate of nonpalpable breast lesions that are missed on mammography, which can be high. TECHNIQUEWe follow the usual technique to localize nonpalpable lesions by means of a hook-wire that is inserted into Fig. 1. Mammogram showing the hook-wire, located in an area of multiple microcalcifications (dotted line circle), and the catheter that is used to insert the dye close to the tip of the hook-wire.