Irradiation of fiber optic waveguides with X-rays, gamma-rays, electrons, or neutrons can cause luminescence and losses in optical transmission. These effects have been measured, using pulsed and continuous radiation sources, in bulk materials and in most commercially available fiber bundles. Some important effects of dopants and impurities such as Ge, Ti, Fe, Al, and OH on radiation-resistance have also been determined. Transient absorption and luminescence were measured from 10 ns to 0.1s after irradiation (10 to 106 rads and 109 to 1013 rads/sec), and the permanent absorption was measured from 24 to 72 hours after irradiation (103 to 109 rads). These results show that synthetic vitreous silica (undoped), some doped silicas, polymethylmethacrylate and polystyrene can be used in radiation environments that are encountered in space and military applications. The utility of each of these fibers depends on the particular radiation environment, the length of waveguide, the wavelength of signal light, the time any system can be “off the air”, and constraints imposed by fiber cost. The data can be used to determine the response of actual fiber systems during and after irradiation.