Radiologically guided localization procedures are indicated pre-operatively when breast lesions are nonpalpable. The results of 42 percutaneous hookwire localizations over a period of 3 years are described. Of the total, 7 (17%) were found to be malignant. Biopsy was indicated by mammographically detected mass in 48%, by microcalcifications in 40% and by microcalcifications with an associated mass in 12%.