This assessment report documents the Nigerian experience in HIV/AIDS treatment in both the public and private sectors. Nigeria accounts for approximately 20 percent of West Africa’s population and is ranked fourth in the world in total number of reported AIDS cases. The impact of the epidemic on the social and economic development of Nigeria has been substantial. HIV/AIDS has contributed to the decrease in life expectancy, increase in the number of deaths in young adults, and increase in the number of orphans in the country. Since 1999, the Nigerian government has placed high priority on HIV/AIDS prevention, treatment, care, and support activities, supported by significant donor efforts for AIDS prevention and control. This assessment was commissioned by United States Agency for International Development (USAID)/Nigeria to gain an in-depth understanding of the current status, challenges, and cost of providing HIV/AIDS services in the public and private sectors in Nigeria. It was a joint undertaking of USAID, the Federal Ministry of Health, and the National Institute of Medical Research.