This paper is dealing with the biomedical applications of active microwave imaging. As a result of extensive preliminary evaluations conducted by means of a 2.45-GHz planar camera, it has been proven that active microwave imaging is able to provide a very sensitive means of investigation in such applications. While technological problems have been conveniently solved, the main problem still remains to determine the most efficient way to process the measured data in order to get the best quality of the reconstructed images. Until now, diffraction tomography algorithms based on a spectral approach have been used. The main limitations of this approach and some attempts to reduce them are analyzed. A more prospective discussion allows to identify the most promising reconstruction techniques. Among them, iterative space-domain formulations appear to provide a suitable base for achieving quantitative imaging thanks to a convenient use of the available a priori information.