Mammography is a branch of radiology which could benefit greatly from the assimilation of digital imaging technologies. Computerized enhancement techniques could be used to ensure optimum presentation of all clinical images. Beyond this it will facilitate powerful new clinical resources such as computer-assisted diagnosis, tele-mammography, plus digital image management and archiving. An essential precursor to all these advances is the availability of appropriate direct digital mammography (DDM) image-acquisition system(s) to capture high-quality breast X-ray image data at the outset. The only practical DDM image-acquisition system currently available is (photo-stimulable phosphor) computed radiography. Modern computed mammography (CM) uses similar radiation doses to the patient and produces equivalent, albeit different, image quality to screen-film mammography. Computed mammography offers superior rendition of the skin edge and sub-cutaneous tissue and dense parenchyma, while ensuring equivalent micro-calcification detectability. Meanwhile, a variety of new technical approaches to DDM are under active investigation and/or development which promise to supercede film-based mammography. These new (second generation) DDM technologies promise the radiologist superior image quality combined with significant dose savings compared with contemporary imaging systems. In this review we describe and compare the physical and clinical characteristics of CM and the various emerging DDM image-acquisition technologies.