The sterile insect technique relies on sterilization of males using ionizing radiation. Life cycle stage, and the environmental conditions under which irradiation is carried out are crucial to the provision of good-quality insects. To identify an optimal radiation strategy for Glossina pallidipes Austen, 1903, 13-day-old males were irradiated at different doses in a nitrogen atmosphere. The following day the males were mated with 8-day-old virgin females. Pupal production of mated females was monitored for 6 weeks, and induced sterility was determined by probit analysis. Survival of the males that mated was also monitored. At least 95% sterility of irradiated males was achieved with a 158 Gy dose in nitrogen and a 125 Gy in air. Irradiation significantly lowered the probability of survival between 30 and 100 days of age (especially flies irradiated in air), but probabilities of survival were similar outside this period for irradiated and unirradiated flies. Exposure of 2- or 13-day-old males to sterilizing radiation induced similar levels of sterility in both air and nitrogen.