The Tri-state STI/HIV project was developed in response to the high rates of sexually transmissible infections in Aboriginal people in central Australia. The project seeks to reduce the prevalence and impact of sexually transmissible infections in the Indigenous Australian population in the cross border regions of South Australia, Western Australia, and Northern Territory. The objectives of the program are three-fold: to better integrate sexual health services into primary health care delivery; improve the coordination of active case finding; and to strengthen regional commitment to STI control. This project has been subjected to several evaluations since its implementation in 1994.