Thailand had been reported as the highest HIV/AIDS epidemic area. Most of HIV/AIDS had been reported from the north of Thailand. Northern Thailand is the favourite living places of hill tribe people who migrated from the south of China through Myanmar last 150 years ago. 600,000 people were living in these areas with differences of culture and life styles. The objective aimed to investigate the situation of HIV/AIDS among hill tribe marginalised and vulnerable population.

Methods The retrospective cohort study was conducted. The systematic data extraction from the medical records in 16 hospitals in northern Thailand during 1990–2010 was performed. The six main hill tribe people: Akha, Lau, Karen, Yao, Kmong, and Lisu were the target population. Chi square test was analysed.

Results Totally 3,130 cases were recruited into the study. 54.6% were males, the first case had been reported in 1990, and the highest incident case had been reported in the year 2004 with 461 cases followed by 2005 (343), and 2006(302) respectively. The highest cumulative case had been reported from Mae Fah Luang Hospital (25.8%), followed by Mae Suai hospital (18.8%). 46.0%were Akha, 19.7%were Lahu, and 9.5% were Yao. 38.8%were 31–40 years old, followed by 21–30 years old(33.6%), and 41–50 years old (13.4%). 44.4%were agriculture, 32.0% were employee. 91.6% were infected by sexual intercourse, 5.7% were mother to Child. 24.0% were receiving ARV, 30.7% were receiving OI treatment, and 9.5% were tested CD4 level. Male had higher of survival rate than female (p-value > 0.001), and male were younger than female at the age of infection (p-value > 0.001). There was statistically significant difference of mode of infection by tribe (p-value > 0.001).

Conclusion Specific health education programmes and empower them for using condom are needed to setting up for HIV/AIDS prevention and control among hill tribe people in Thailand.