Ultrasonography of the breast effects the visualization of the delicate anatomical structures of the mammary gland, including the galactophorous duct, the connectivo-glandular cones and the fat lobules. This technique is very helpful in the differential diagnosis of benign and malignant breast lesions by defining the edge of the lesion, its depth and width diameters as well as by attenuation. In addition, breast ultrasonography permits cyst drainage and / or aspiration biopsy of nonpalpable and radiologically negative breast lesions under visual control.