A light guide (1) formed from an unclad flexible polyurethane fiber produces significant side scattering (2) over distances of up to several meters. The polyurethane fiber is in the form of a solid fiber or a tube and may comprise light scattering particles. The polyurethane fiber may comprise a transparent flexible polyurethane UV resistant outer cladding. Embodiments include illuminated shoe laces, a power cord safety indicator, an illuminated dental suction tube and a dental curing tip.