Research to determine knowledge, attitudes, practices in HIV prevention of men who have sex with men (MSM) in Khanh Hoa province in 2010. There are 455 MSM study participants with all the sampling method as a result of mapping the social geography. The results showed that the majority of MSM have good knowledge about the spread of HIV/AIDS. 47.5 percent answered correctly from 14 to 15 questions about knowledge of HIV/AIDS transmission and prevention, but still 30 percent of MSM having thought of anal sex is not at risk. To attitudes, there was 61.5 percent of MSM have not discussed with male sexual partners of HIV or other STls as anal sex does not pay. MSM rate in urban discussed with partners was 76.3 percent higher than in rural (51 percent). To practices, there was 99.1 percent had used condoms during sex but in the most recent sexual encounters anal pay (78.6 percent) and 65.7 percent did not use condoms when having sex with women. The major source of condoms (87.9 percent) and water-soluble lubricants (96.2 percent) were providad from peer educators. Only a low percentage of MSM (19.6 percent) have received counseling and support for HIV. There was 5.7 percent of MSM in the study had used drugs and 2 percent had injected drugs.