INTRODUCTION AND OBJECTIVE: In the light of current data concerning the growing exposure to ionizing radiation (IR) originating from atrificial sources, especially from medical ones, and also related to occupational exposure, it is justifiable to systematize the state of knowledge concerning the effect of IR on the male reproductive system. BRIEF DESCRIPTION OF THE STATE OF KNOWLEDGE: There is no basis for the application of the hypothesis of hormesis in the area of male reproductive health. Regarding the impact of IR on spermatogenesis, spermatogonia are less susceptible to the occurrence of DNA damage after exposition to IR, but are characterized by slower DNA repair compared to somatic cells. Damage to the genes after exposure to IR is possible at each stage of spermatogenesis; however, haploidal spermatids show the highest radiosensitivity in this respect. The genetic risk of the cells differentiating during spermatogenesis is limited to one cycle of spermatogenesis, whereas the genetic instability may persist for the whole period of life, and DNA damage induced by IR may be transmitted to future generations. The minimum dose causing detectable DNA damage was 30 Gy. While exceeding this dose, the number of single-strand DNA breaks increases. Among males exposed to IR, a decrease was observed in sperm motility and in the percentage of morphologically normal spermatozoa as well as in an intensification of vacuolization. The genetic material in the sperm of these males showed higher fragmentation and methylation of genomic DNA. CONCLUSION: In the context of the epidemiological situation concerning the prevalence of infertility, while assessing the health effects of exposure to IR from artificial, including medical sources, the reproductive risk should be considered.