Abstract.The application of laser-based X-ray sources to medical imaging has been investigated theoretically and experimentally. Two modalities were emphasized: mammography and dual-energy subtraction angiography (DESA). We have established that an ultrafast laser-based X-ray source can produce very small X-ray spots and can provide narrow X-ray spectra specifically tailored to the imaging task (patient thickness, tissue density, type of X-ray contrast, etc), thus providing greatly improved contrast and spatial resolution as well as better dose utilization, as compared to the X-ray tube. The most appropriate femtosecond laser systems for clinical applications are higher repetition rate lasers (from a few hundreds of Hz to a few kHz), because they are compact, reliable and they do not require complex beam manipulation in the vacuum. Presently, the ultrafast laser average power is a critical issue, but we expect to be able to meet power requirements for mammography within next few years. The ultrafast laser system required for DESA will have to work with an X-ray monochromator and it will need to produce an average power that is over an order of magnitude higher than the average power needed for mammography.