The conventional approach to localization of impalpable breast lesions, i,e. employing a hooked mire with either stereotaxis or a perforated plate, has potential disadvantages for the operating surgeon, Often the entry point of the wire lies some distance from the site of projection of the lesion on the skin, The guide-wire should pierce the skin at, or close to, the site of any proposed surgical incision and proceed along the shortest and most direct course towards the lesion. Ideally, the wire should lie within a radial distance of between 1 and 2 cm from its target, A method is described which achieves these objectives and involves both radiological and clinical measurements. A total of 665 guide-wire localized biopsies have been carried out at the above institutions between 1 November 1987 and 31 March 1995 and between 1 January 1994 and 31 March 1996. In only 4% of cases was re-positioning of the wire required. Excision of the radiological lesion mas obtained with a single biopsy in 99% of cases. A second or third biopsy was indicated in 0.7% and 0.3% of cases, respectively, Migration of the wire occurred in two patients and no cases of wire transection or pneumothorax were reported, This method of localization facilitates subsequent excision and permits the most appropriate incision consistent with optimal cosmesis.