In 1993 three institutes belonging respectively to the Heidelberg Academy for Humanities and Sciences, to the Russian Academy of Sciences, and to the Russian Academy of Medical Sciences, launched a cooperative research project. The main aim of the project is to develop mathematical methodologies needed for better information support in health policy decision-making in the area of primary health care provision for the Russian populations affected by radiation due to the Chernobyl accident. At present, the major data basis of the project is the Russian National medical and Dosimetric (Chernobyl) Registry administered at the Medical Radiological Research Centre, Obninsk. The book describes the general mathematical approaches to the project and the given conditions of the registry.