OBJECTIVES: To describe the key financial resources allocation supporting the HIV/AIDS prevention, treatment, and social support programs in Thailand and to identify facilitators and barriers in financial management and monitoring system.   METHODS: Based on a comprehensive review of financial reports from various sources such as UNGASS, NASA and NAMC reports, we explored the key financial resources that support the HIV/AIDS prevention, treatment, and social support programs in Thailand. In addition, we conducted in-depth interviews with different key informants responsible for the activities in response to the national policy on HIV/AIDS in provincial and district levels including domestic and international donors to assess the financial management, coordination and monitoring system. RESULTS: The total expenditure on HIV/AIDS in fiscal years 2007, 2008 and 2009 were 204, 210, and 218 million US$, respectively. The national HIV/AIDS spending was amount to 2.7% (2007) and 1.9% (2008 and 2009) of the total health expenditure. Domestic funding accounted for 83%, 85% and 93% of the HIV/AIDS programs in 2007, 2008 and 2009. Much of those spending emphasized on care and treatment while prevention budgeted for 14.1%, 21.7%, and 13.7%. The majority of treatment financing came from public health insurance schemes, but most preventive programs were from GFATM and other international sources. Effective system development in program management, monitoring and evaluation are still lacking among practitioners. CONCLUSIONS: Thailand has shown its potential to be self-reliant in combating HIV/AIDS. Nevertheless, care and treatment expenditures overshadow prevention, and most of the preventive programs are from international sources. Thus, the dominance of entitlement programs in funding for HIV/AIDS treatment challenges policy makers to monitor the extent and quality of HIV/AIDS care. For future savings in the cost of treatment and care, investing in prevention programs is essential, especially due to the declining support from international funds.