The Magu Health and Demographic Surveillance System (HDSS), an open community cohort, was established in 1994 in a rural area with seven contiguous villages in north-western Tanzania to study HIV epidemiology. Over time, new data sources such as the national surveys from 2004 and clinical tracking systems have filled much of the knowledge gap on HIV epidemiology in Tanzania. The launch of the 2030 Sustainable Development Goals meant an important broadening of government health strategies in Tanzania and universal health coverage became a priority, requiring new population research inputs. The population under demographic surveillance expanded from 19?347 in 1994 to 54?024 in 2022 - a population growth of 3.7percent per year. The main priority areas of research include patterns and inequalities in mortality and causes of death, health service utilization and health expenditure, mortality and health-seeking behaviour among children aged >5 years, sexual and reproductive health among adolescents, and linked analyses of research and routine service data. Magu HDSS data are held at the National Institute for Medical Research office in Mwanza and are also available through several international initiatives and networks including iSHARE, INDEPTH and ALPHA.