The radiation oncogenesis is a theme well defined from the nosological point of view by the "Evidence Based Medicine" (EBM) founded on sound scientific and on sound medical evidences. Radiobiology and radioepidemiology are the scientific and medical branches for this purpose. The very huge number of collected data analysed by numerous international and national scientific organisms (RERF, NIH, BEIR, ICRP, IARC, UNSCEAR) (1-9) can individuate the more susceptible organs and tissues to radiation cancer and the extent of their susceptibility by the evaluation of the relative risk related mainly to dose but also to other exposition parameters. So it is now possible to categorize many organs and tissues bearing in mind their specific susceptibility to cancer induction by ionising radiation. The author on the basis of the literature data propose a scale to categorize the interested organs and tissues in "very high", "high", "medium" and "low" steps of susceptibility to radiation cancer. The aim of this is to give an indicative aid to the occupational physicians actuating the medical surveillance on the radiation exposed workers.