Background AIDS is a desease that can decrease immune system of our body through many kind of desease that was caused by HIV infection. Indonesia is one of countries in Asia with the highest prevalence of HIV/AIDS. Based on KPA (Komisi Penanggulangan AIDS), there are 361 cases of HIV/AIDS in the municipality of Yogyakarta until 2009, 40 – 50 % of them have oral health problem. HIV/AIDS can have an oral manifestation exposure and this is very important to know because sometimes it can be the first indication of people who has infected by that disease. Aim The purpose of this study is to find out the knowledge description of people with HIV/AIDS on the oral manifestation of that disease in the municipality of Yogyakarta Method Thirty people with HIV/AIDS at NGO Kontras and NGO Dimas Diajeng Support Yogyakarta comprised of 12 males and 18 males were chosen purposively and were used as an observational study sample with cross sectional design. A questionare was used to asses the knowledge of the samples on the oral manifestation of HIV/AIDS. A descriptive analysis was used to find out the knowledge description of samples with HIV/AIDS on the oral manifestation of the disease. Result The result shown that among 30 samples, 3 (10%) of them hold good knowledge, 14 (46,67%)sample hold sufficient knowledge, 9 (30%) samples hold poor knowledge and 4 (13%) samples hold very poor knowledge on oral manifestation of HIV&ADIS. while 2 (6,67%) females and 1 (3,3%) males hold good knowledge respectively, Seven (23,37%) females and 7 (23,37%) males of samples hold sufficient knowledge, 7 (23.37%) females and 2 (6,67%) males hold poor knowledge and 2 (6,67%) females and 2 (6,67%) males of samples hold very poor knowledge on the oral manifestation of HIV&AIDS respectively. Conclusion It can be concluded that almost half of samples hold sufficient knowledge on the oral manifestation of HIV&AIDS, and male samples tend to hold better knowledge then females samples.