- Cambodia, Kingdom of Cambodia
- Cambodia, Kingdom of Cambodia, National Center for HIV/AIDS, Dermatology and STD
- Cambodia, Kingdom of, National AIDS Authority (1999 - )
- Canadian International Development Agency (1968 - )
- CARAM Asia (1997 - )
- Care and support
- CARE Australia (1987 - )
- CARE Canada (1946 - )
- CARE International (1945 - )
- CARE Japan
- CAS
- see Center for Advanced Study (1996 - ) - CDC Taiwan
- see Division of AIDS and STD, Centre for Disease Control (1999 - ), Taiwan, R.O.C. - CDC, People's Republic of China
- see National Centre of AIDS and STD (1998 - ), China, People's Republic of - Center for Advanced Study (1996 - )
- Center for Strategic and International Studies (1962 - )
- Centre for Harm Reduction, MacFarlane Burnet Institute for Medical Research and Public Health
- Centre for International Health (1986 - ), MacFarlane Burnet Institute for Medical Research and Public Health
- CFR
- see Council on Foreign Relations (1921 - ) - Children/Orphans
- China, People's Republic of China (PRC)
- China AIDS Survey
- China, People's Republic of, National Centre of AIDS and STD (1998 - )
- Chinese Taipei
- see Taiwan, Republic of China, R.O.C. - Christian Aid (1945 - )
- CIDA
- see Canadian International Development Agency (1968 - ) - Civil Society Organisations (CSOs)
- see NGOs - Coalition of Asia Pacific Regional Network on HIV/AIDS
- see Seven Sisters (2001 - ) - Co-infection
- Commercial sex workers
- see Sex workers and clients - Commonwealth of Australia, Australia
- Commonwealth of the Northern Mariana Islands, Northern Mariana Islands
- Commonwealth Secretariat (1965 - )
- Communications programming
- Community based care
- see Home and community-based care - Community Based Organisations (CBOs)
- see NGOs - Community mobilisation
- Condoms
- The Consortium for Social Policy Research on HIV, Hepatitis C and Related Diseases
- Constella Futures (1971 - )
- Cook Islands
- Coordination of Action Research on AIDS & Mobility
- see CARAM Asia (1997 - ) - Cost-effectiveness analysis
- Council on Foreign Relations (1921 - )
- Counselling
- CSIS
- see Center for Strategic and International Studies (1962 - ) - Cultural Determinants
- see Determinants of the epidemic - Custodial settings
- see Prisons