1. The effects of 400 and 575 rads of whole body irradiation in gerbil (Meriones hurrianae), hedgehog (Hemiechinus auratus Collaris) and house rat have been studied with a view to compare the effects of irradiation on the desert mammalian species with those of domestic ones. 2. Typical signs and symptoms of radiation sickness, transient body loss and radiation mortality in gerbils and house-rats were apparent, whereas the hedgehogs were not affected at this dose level. 3. Extensive necrosis, exfoliation of seminiferous element, intertubular edema and shrinkage of the seminiferous tubule and Leydig cell nuclei in gerbils and house-rats were conspicuous in histological preparations. Mild regressive tubular lesions were also observed in hedgehogs treated with 575R. 4. Whole body irradiation depleted the RNA, protein and sialic acid contents of the testes. High cholesterol contens in the testes of irradiated gerbil, hedgehog and house rats identified this as the site of degenerating cells and fragments. 5. Reduced androgen production was confirmed in non active Leydig cells and decreased fructose contents in the seminal vesicles of gerbil and house rats. At 575 R dose level, hedgehog was comparatively radio-resistant. But at 875 R extensive damage to the reproductive organs could be noticed.