Most of the basic data regarding the effect of radiation on the testis are issued from animal studies. They demonstrate the extreme radiosensitivity on the germ cell lineage but little is known about the reversible or definitive aspects of these radiation induced effects. In man, the late non stochastic effects of radiation to the testicule are mainly related to persisting spermatogenesis disturbances or/and hormone related problems. Morphological, physiological, radiobiological specificities of the human testis along with numerous parameters depending on radiation conditions make it difficult to evaluate the late effects and radiation tolerance doses. Evaluation of such effects based on a common scale for therapeutic radiation schedules would improve the present understanding and possibly prevent the occurrence of these delayed effects, for the benefit of patients.