Exposure to X-ray during late pregnancy has a major impacton the developing testis. The aim of this work was to study theeffect of exposure to X-ray at the age of 15 and 20 days ofgestations on the foetal testis. Exposure was done using variabledoses of radiation and the testes of male offspring were weighedand studied by light and electron microscope as well as the imageanalyzer computer system. It was noticed that exposure at the 20thdays of gestation has more adverse effects on the developing testisthan exposure at the 15th gestational day. These changes areproportional to the dose of radiation exposure and becomeprogressively more profound with increasing age of the offspring