This chapter describes the possibility to use Digital Holography as a tool to carry out a non-contact and non-destructive characterization and inspection of micro-electro-mechanical systems (MEMS). The technique allows to evaluate quantitatively, with high accuracy, different features of a typical MEMS: the profile; the deformations induced by external influences; the behavior when actuated under operation conditions. Digital holography provides two main advantages consisting in the possibilities to perform a dynamic characterization of the MEMS and to reconstruct the in-focus image of the object for 3D structures. The evaluation of the MEMS performance is particularly useful when studying and understanding the effectiveness of the design and of the fabrication process. Several examples of MEMS inspection are illustrated to demonstrate the reliability of the technique.