Renáta Szabóová, Katarína Beňová, Martina Galdíková, Robert Herich, Beáta Holečková, Viera Schwarzbacherová - This textbook is intended for students and provides basic information and orientation in the study subject "Radiobiology". For a student of veterinary medicine, it is important to understand the basic rules, differences, mechanisms of radiation action at the level of cells and tissues and the organism, radiation protection, clinical manifestations/radiation syndromes of acute and late effects of ionizing radiation on the organism. The aim of radiobiology is to reveal the general laws of the reaction of a living organism to the action of ionizing radiation. Thanks to this specific focus, radiobiology appears as an independent complex scientific discipline, which is connected with a lot of information from theoretical and practical scientific areas, e.g. with biology, physiology, cytology, genetics, biochemistry, biophysics and nuclear physics. The study of basic radiobiological mechanisms deals with biological effects caused by the absorption of energy in small volumes corresponding to the level of individual organ systems, organs, cells or parts of cells.