Men who have sex with men (MSM) are a vanguard population in the HIV epidemic, but there are limited data about MSM in Viet Nam. We conducted two surveys, using the same questionnaire but two different sampling strategies, to examine sociodemographic characteristics, sexual identities, and key indicators of HIV risk among Vietnamese MSM.

The network recruitment survey, June-October 2008, employed respondent driven sampling (RDS) among MSM in Ha Noi, Viet Nam. 402 MSM self-administered a questionnaire. The population accessed in the RDS survey was mostly young (75.9% were under 25 years old), and well-educated (60.3% had attended some college). 56.2% self-identified as gay, 15.2% as bisexual, and 11.6% as "straight". About one-fifth had ever been paid for sex with a man. The proportions of men practicing consistent condom use with different types of male partners were 45-50%. One-third of men were able to give correct answers to five questions on HIV transmission and prevention. Only 31% of the men considered themselves at risk of HIV.

The Internet-based survey, conducted November 2008 to February 2009, recruited Vietnamese MSM through gay websites. A total of 2,640 respondents provided complete sociodemographic information. 62.9% were younger than 25 years; nearly 80% had attended some college. 63.4% self-identified as gay and 17.7% as bi-sexual. 39.8% of men who had anal intercourse with other men during the past 6 months did not use a condom during the last anal sex, especially if they did not think they were at risk of HIV (relative risk (RR): 1.4; 95%CI: 1.1-1.6) and/or if the partner was a regular partner (RR: 1.5; 95%CI: 1.2-1.9).

Compared to the Ha Noi MSM recruited through network sampling, respondents to the Internet survey had more education and income, better knowledge of HIV, and higher personal risk perception.

Results of this study provide detailed sociodemographic information about MSM in Viet Nam and confirm that many are at high risk of HIV. HIV prevention interventions for MSM should be scaled up and possibly conducted in partnership with MSM websites.