Polymer optical fibres (POFs) have historically been regarded as a poor relation to their silica counterparts because of their higher attenuation, but they also have a number of advantages, particularly when coupled with a range of properties that can be produced using microstructures. In terms of their mechanical properties, they are lighter, remain flexible at large core sizes and can be stretched well beyond 30% without breakage. They are also biocompatible, they do not produce dangerous shards, and their low processing temperatures allow functionalized organic materials to be incorporated without decomposition. ther advantages for specific applications include better transmission properties (in the THz region) and the possibility of refractive indices that are close to that of water.