An investigation was made on the effects of pulsed ionizing radiation on the attenuation of SiO2 fiberoptic waveguides doped with GeO2, B2O3 and P2O5. Data were taken over time, temperature, and wavelength ranges of interest for long-length fiberoptic communication applications. For fibers containing only GeO2 and B2O3, operation at 1.06 µm reduced by a factor of approximately 10 the radiation sensitivity among the fibers examined when compared with 0.8-µm operation. The fiber with the lowest GeO2 content (before deposition) showed the lowest radiation sensitivity of the fibers investigated. For systems applications, attention should be paid to operation at low temperature where large radiation-induced losses could persist at both wavelengths for long times following the irradiation pulse. The addition of small amounts of phosphorus reduced the low-temperature response, but also increases the radiation sensitivity at high temperatures. Copyright © 1978 by The Institute of Electrical and Electronics Engineers, Inc.