Abstract: Objective To analyze prevalence characteristics of human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS) among Mongolians in Inner Mongolia Autonomous Region (Inner Mongolia).Methods Data on all HIV/AIDS cases reported in Inner Mongolian by the end of September 2015 were collected form National Notifiable Disease Report System via direct reporting network.Results There were significant differences in age,gender,occupation,marital status,and educational level among Han,Mongolian and other minorities HIV/AIDS cases (P<0.001 for all).Of the reported Mongolian HIV/AIDS cases,73.1% were unmarried males aged 20-30 years;10.8% were students and the ratio was two times higher than that of Han (5.4%) and other minorities (4.7%) cases;60.1% had the history of having sex with men;19.4% had the history of sexually transmitted diseases;and 60.3% were infected via homosexual transmission;all the ratios were significantly higher than those of the Han and other ethnic minorities cases (all P<0.05).Among the reported Mongolian HIV/AIDS cases,23.8% were identified through counseling and testing and 24.3% through provider-initiated testing,and the two proportions were significantly higher than those among reported cases of other minority ethnic groups (χ²=1 083.56,P<0.001),of which,49.3% were identified in physical examinees under compulsory detoxification or detainment.The reported Mongolian HIV/AIDS cases had significantly higher ratio of delay in diagnosis and treatment (both P<0.001) and higher AIDS-related mortality (χ²=27.59,P<0.001) compared to the cases of other minority ethnic groups but lower ratio of staying in local area (8.6% vs.15.0% and 21.3%) compared to the cases of Han and other minority ethnic groups (both P<0.001).Conclusion Male homosexual behavior is a major route of HIV/AIDS transmission among Mongolians in Inner Mongolia and effective intervention should be carried out among Mongolian men who have sex with men.