Tomographic Diffractive Microscopy (TDM) is an advanced digital imaging technique, extending the concept of Digital Holographic Microscopy (DHM), which provides quantitative information about the index of refraction distribution within the observed sample, by recording of multiple holograms under varying conditions of illumination, then applying numerical inversion procedures to reconstruct a 3-D image of the specimen under consideration. After a short recall of DHM applications and limitations, various implementations of TDM are described, highlighting their respective advantages and. drawbacks. To conclude, some perspectives and challenges for this imaging modality are presented.