Ionizing radiation during the whole developmental phase induces high radiation sensitivity in the human embryo and fetus. Particularly in the phase of organogenesis, increased malformations result in a lower quality of life for the fetus after birth. In a suspected or existing pregnancy, it is, therefore, necessary to limit the indication for examination or treatment of the mother with ionizing radiation or radioactive elements more than in other phases of life. The probability of unfavorably influencing development in the womb by ionizing radiation depends on the dose received by the fetus. For this reason, all measures should be taken to keep the radiation exposure to a minimum. Since up until now no uniform recommendations regarding indication for therapeutic abortion following irradiation have been drawn up in Western Germany, it is advisable to fall back on those recommendations drawn up by Scandinavian countries on the basis of thorough radiobiological knowledge and experience. In cases where the probability of unfavorable effects exceeds 10% and/or the natural malformation rate doubles, a therapeutic abortion should be considered. In a properly conducted examination, this level is generally not reached. A few tips are also presented in regard to the proper execution of the examination during pregnancy.