During the last decade it has been proven that focused femtosecond laser pulses are an ideal tool for micro- and sub-micro-structuring of all kinds of materials. Due to the high intensities that can be achieved in ultrashort pulses they can be applied for machining transparent media within the volume by means of multi-photon absorption. Besides ablative methods, multi-photon absorption can also lead to photo-polymerization of light-sensitive resins, i.e. two-photon polymerization. In this paper we present our latest results on the fabrication of 3D microstructures by means of two-photon polymerization.© (2004) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.