Myanmar has an extensive and growing HIV/AIDS epidemic. The areas with the highest incidence seem to be townships and economic hubs along the Thai and Chinese borders, such as Tachileik, Lashio, Kyaingetong (Keng Tung) in Shan State, Myitkyina in Kachin State, and Dawei and Kawthaung in Tanintharyi Division, and the major cities of Yangon and Mandalay.

HIV prevalence rates among injecting drug users in Yangon and Mandalay have not fallen below 60% since 1992, according to biannual sentinel surveys. While IDUs still account for the majority of HIV/AIDS cases reported to the Ministry of Health, the situation is changing. Recent figures indicate that the epidemic is now spreading through the general population, primarily by sexual transmission. HIV infection rates among female sex workers are alarming – 47% in the September 1999 sentinel survey, even higher in Yangon and Mandalay. Rates among women attending antenatal clinics rose from 0% to 1.79% between 1992 and 1998. A 1999 study found HIV prevalence in women was highest in the 15-19 age range.

Migration is a key factor in the epidemic's expansion, caused by poverty, lack of opportunities and long-running internal conflicts. Young people, many from ethnic minorities, are on the move in the border areas. Up to a million migrants from Myanmar are currently working in Thailand, while significant numbers also migrate to southern China and India. Most of these cross-border migrants have no official papers, so they cannot access prevention and care services. Their undocumented and illegal status also dramatically increases their vulnerability to exploitation. Many are unable to speak the language of their host country and end up in low-paid sex work, seafaring or construction labour, where they are highly vulnerable to HIV infection and have little or no access to HIV/AIDS information.