The introduction of low-loss optical fibers (<20 db/km) has led to their increased use in optical communications and data acquisition systems. Optical fibers have intrinsic advantages over wire bundles. However, the application of ionizing radiation (gamma rays, X-rays, and electrons) causes increased attenuation (loss of transmission) in the fibers. This paper summarizes the various ex-perimental facilities and optical systems used by investigators to study the effects of ionizing radiation on optical fiber waveguides. The applicable equations used by investigators to express optical fiber transmission loss and absorption are summarized. Recent results from irradiating silica optical fibers doped with phosphorus, boron, and/or germanium are presented. The effect of temperature on transmission is discussed. Transient recovery mechanisms such as geminate recombination and tunneling, as applied to irradiated fiber optic waveguides, are reviewed. Areas meriting further investigation are outlined.