Polyimides, a class of advanced polymer materials with high performances characterized by outstanding thermal stability, mechanical, electrical and solvent resistance properties originating from their rigid backbones, often find extensive applications in photoresists, passivation and dielectric films, soft print circuit boards, and alignment films within displays. The main obstacles that seriously limit the applications of aromatic polyimides in optoelectric materials and high-speed multilayer printed wiring boards are their insolubility in common organic solvents in the fully imidized form, the light or dark-yellow color of their films caused by intra- and intermolecular charge transfer (CT) interactions, and their high dielectric constants. In recent years, polyimides with high optical transparencies and low dielectric constants have been in demand for optoelectronic and microelectronic applications. Alicyclic and aliphatic polyimides are candidates for applications in optoelectronics and interlayer dielectrics due to their higher transparency and low dielectric constants when compared to aromatic polyimides. These properties result from their low molecular density, low polarity, and low probability of undergoing inter- or intra-molecular charge transfer. Accordingly, great effort has been made to synthesize new aliphatic/alicyclic dianhydride or diamine monomers. I will talk on a few novel polyimides having improved transparency that have been reported in my laboratory for years. Keywords: polyimides, transparency, flexible substrate, advanced polymer materials