Breast cancer is the most common female cancer, and the second cause of cancer-related mortality of women in our society. Mammography is the gold-standard method of breast imaging. However it is not an optimal screening tool, especially in cases of dense breast parenchyma. Even when optimally performed, its sensitivity ranges between 69 and 90%. Ultrasound represents an additional diagnostic tool that raises the detection rate of benign and malignant breast lesions. It is the method of choice for differentiating solid from cystic lesions, for further characterizing mammographic findings and better appreciating palpable breast lesions. B-mode ultrasonography is used in every day practice. Harmonic imaging and compound imaging can be used to ameliorate the image contrast and resolution. Colour Doppler is used for studying lesion vascularization however there is no consensus as to whether it really permits to differentiate malignancies from benign lesions. New technical developments such as breast elastography, 3D ultrasound and dedicated ultrasound computed aided diagnosis (CAD) are promising methods for the future.