In microsystem technology the fabrication of either passive or active micro optical components made from polymers becomes more and more evident with respect to the intense expanding application possibilities e.g. in telecommunication.Actually the LIGA process developed at the Forschungszentrum Karisruhe (FZK), Germany, (LIGA is the german abbreviation of lithography with synchroiron radiation, electroplating and molding) allows the direct fabrication of microcomponents with lateral dimensions in the micrometer range, structural details in the submicrometer range, high aspect ratios ofup to several hundreds and a fmal average surface roughness ofless than 50 nm in small up to large scales. The molding ofpolymer components for microoptical applications, especially in the singlemode range, is determined by the achievable maximum accuracy of the molding technique itself and of the acceptable tolerances for low damping and coupling losses. Following the LIGA and related techniques e.g. mechanical microengmeering we want to present in this work the fabrication ofpolymer singlemode waveguides using a combination ofmicromolding and light-curing steps.