Invasive localization procedures are indicated preoperatively when breast lesions are nonpalpable. Several techniques are available for locating such lesions. In experience with 343 nonpalpable lesions, 27% of the biopsied lesions were malignant. Calcification was present in 51% of all lesions. A combination needle-hooked wire technique was used. Some problems were encountered, the most frequent being vasovagal reactions. The most serious problem was the failure to remove the located lesion in nine cases.