Purpose: To evaluate the role of ultrasonography (US) as a method of guidance for fine-needle aspiration biopsy or preoperative wire localization in the demonstration of nonpalpable mammographically detected breast lesions Material and Methods: A total of 168 nonpalpable mammographically detected breast lesions were examined by means of high-resolution real-time US Results: US depicted: 55% of all the lesions (92/168); 88% of the circumscribed densities (45/51); 80% of the stellate densities (35/44); 47% of the asymmetric densities (7/15); and 9% of the microcalcifications (5/58) Conclusion: US was useful in guiding needle biopsy or wire localization in most of the circumscribed and stellate breast lesions, even in fatty breasts. However, with the equipment that is currently available, US was of no value in localizing microcalcifications