Objective: During the last 15 years, the suicide rates have declined in Sweden and Denmark, but rather stable in Norway.The purpose of this study is to compare suicide registration in the three Scandinavian countries, and to evaluate potential sources of error.Methods: Information about suicide registration was obtained from Statistics Norway and the National Board of Health and Welfare in Sweden and Denmark.In addition we received information from experts in this field from each country.Results: Mortality registrations are based on the medico-legal system in all three countries according to the 10th version of the International Classification of Diseases (ICD-10), developed by the World Health Organization (WHO).The last years all three countries have used ACME (Automated Classification of Medical Entities), a software that selects the underlying cause of death based on ICD-codes.Denmark and Sweden have started to use electronic death certificates, in contrast to Norway, where one still write the death certificate on paper.Several studies have concluded that suicide is underreported, and that there are many hidden suicides in the diagnosis group undetermined intent.In 2009 Denmark reported 4,471 ill-defined and unknown causes of mortality (R95-R99, except sudden infant death syndrome), while Sweden reported 1,533 and Norway 1,520.Conclusion: Suicide registrations are quite similar in the three Scandinavian countries, but there are some different national traditions for the choice of manner of death, where Denmark uses undetermined intent more often than Sweden and Norway.Automatic encoding may not necessarily provide a more accurate cause of death statistics, but it will provide greater consistency in the coding, thereby increasing the comparability between countries.