The Swedish cause of death register is a high-quality, nearly complete record of all deaths in Sweden since 1952. It is used for official statistics and medical research, and can be linked to other national registers containing data on social and health factors. The register was established in 1749 and has undergone several changes, including the adoption of WHO standards in 1951. The National Board of Health and Welfare has been responsible for the register since 1994. The register uses the international version of the ICD classification system, with minor annual updates and major updates every three years. Death certification in Sweden involves two stages: a notification to the tax authority and a medical death certificate to the National Board of Health and Welfare. The underlying cause of death is defined as the disease or injury that directly led to death, or the circumstances of an accident or violence. The process of identifying the underlying cause is complex and follows ICD-10 guidelines. Forensic death investigations are common, especially for unnatural deaths, and involve full autopsies and toxicology testing. The register includes individuals who died in Sweden regardless of residency. Before 1991, the death certificate was legally required for burial, ensuring completeness. Since 1997, all notified deaths have been included in the register. The quality of the register is influenced by the accuracy of death certification and the consistency of coding practices. Studies show high agreement between the register and medical records for certain diseases. The register has strengths in completeness and long-term data availability, but weaknesses include potential data inaccuracies and challenges in merging data with other registers. The main causes of death vary by age and sex, with cardiovascular diseases and cancer being significant causes. Over time, there have been changes in the proportion of deaths due to different causes. The register is a valuable resource for both official statistics and research.The Swedish cause of death register is a high-quality, nearly complete record of all deaths in Sweden since 1952. It is used for official statistics and medical research, and can be linked to other national registers containing data on social and health factors. The register was established in 1749 and has undergone several changes, including the adoption of WHO standards in 1951. The National Board of Health and Welfare has been responsible for the register since 1994. The register uses the international version of the ICD classification system, with minor annual updates and major updates every three years. Death certification in Sweden involves two stages: a notification to the tax authority and a medical death certificate to the National Board of Health and Welfare. The underlying cause of death is defined as the disease or injury that directly led to death, or the circumstances of an accident or violence. The process of identifying the underlying cause is complex and follows ICD-10 guidelines. Forensic death investigations are common, especially for unnatural deaths, and involve full autopsies and toxicology testing. The register includes individuals who died in Sweden regardless of residency. Before 1991, the death certificate was legally required for burial, ensuring completeness. Since 1997, all notified deaths have been included in the register. The quality of the register is influenced by the accuracy of death certification and the consistency of coding practices. Studies show high agreement between the register and medical records for certain diseases. The register has strengths in completeness and long-term data availability, but weaknesses include potential data inaccuracies and challenges in merging data with other registers. The main causes of death vary by age and sex, with cardiovascular diseases and cancer being significant causes. Over time, there have been changes in the proportion of deaths due to different causes. The register is a valuable resource for both official statistics and research.