Clinically, there are two important issues in breast imaging: detection of microcalcifications and identification of mass lesions. X-ray mammography is the main imaging method used for detection of microcalcification, and ultrasound imaging is normally used for detection of mass lesions in breast. Both these methods have limitations that reduce their clinical usefulness. For this reasons, alternative breast imaging modalities are being sought. vibro-acoustography is an imaging modality that has emerged in recent years. This method is based on low-frequency harmonic vibrations induced in the object by the radiation force of ultrasound. This paper describes potential applications of vibro-acoustography for breast imaging and addresses the critical imaging issues such as detection of microcalcifications and mass lesions in breast. Recently, we have developed a vibro-acoustography system for in vivo breast imaging and have tested it on a number of volunteers. Resulting images show soft tissue structures and calcifications within breast with high contrast, high resolution, and no speckles. The results have been verified using X-ray mammography. The encouraging results from in vitro and in vivo experiments suggest that further development of vibro-acoustography technology may lead to a new clinical tool that can be used to detect microcalcifications as well as mass lesions in breast.