The Nordic countries have a unique potential for conducting valuable health research using the national health data sources. The existence of personal identity numbers in combination with a high degree of public trust in research, makes health registry research on combined large-scale datasets possible. Use of health data from registries in medical research is advantageous in several ways. First, this type of data is reality based, and may be used when the traditional randomised controlled trials are not possible. The registries are excellent for longterm follow-up, and as they are national and mandatory, they provide an unselected, unbiased population sample. One of the main obstacles for making use of this great potential is issues concerning regulations of use of the data, and sometimes bureaucracy and legislation makes access cumbersome. The health data should be used far more and often, and obstacles concerning data sharing across borders must be reduced. The society needs new knowledge, and we must aim to conduct more research, provide better research and base the research on real time data in order to get the results faster.