Abstract: Inexpensive, highly efficient, flexible, fiber optic light guide which includes a plurality of flexible optic fibers which are unclad along their length and arranged in a bundle to increase packing density with all the ends of the fibers of the bundle falling in common planes at the entry and exit ends of the light guide. The flexible optic fiber bundle is provided with a suitable protective cladding which also may include a layer of clad optic fibers that surround the bundle. Light incident at one end of the light guide is reflected internally along the longitudinal length of the guide by a cladding boundary or space boundary so that transmission losses are minimized. Suitable ferrules may be provided at each end of the light guide.