The Kisesa HIV open cohort that was established in 1994 to monitor the trend and impact of the HIV/AIDS epidemic at the general population level has been a successful endeavour. The cohort is the 3rd longest continuous running HIV cohort in sub-Saharan Africa. The study monitors vital demographic events in Kisesa ward in Magu district, Mwanza Region. The cohort is linked with demographic, epidemiological, antenatal surveillance systems and other nested studies. Results from the Kisesa demographic surveillance site have influenced the formulation of national policy and practice in various ways.