HIV prevalence remains high in men who have sex with men (MSM) in Bangkok. Even though resources for HIV testing and treatment are available for all, a large proportion of MSM still do not get HIV tested. We studied high risk MSM who are unaware of their HIV status to help maximize effectiveness of our resources. Convenience sampling was conducted among MSM who came for HIV testing at the Thai Red Cross Anonymous Clinic and two popular drop-in centers in Bangkok. Inclusion criteria were MSM aged >18years, have not been tested positive for HIV, who reported ≥1 of the following in the previous 6months: condomless sex with a male, being a sex worker, or having a sexual transmitted infection diagnosis. Audio-Computer-Assisted Self-Interview was used to assess psychosocial profile, sexual risks, and HIV testing patterns prior to being informed of their HIV positive status. Among 499 high-risk MSM enrolled, themedian age was 24.8years and 112 (22%) tested HIV-positive. Among the HIV-positive participants, 92% self-identified as gay (versus bisexual), 39% attained a bachelors degree or higher, 65% had monthly income 10,000-29,999 baht ($280-830 USD), 10% had vaginal or anal sex with a woman in the past 12months, 39% had condomless receptive sex with men and 21% went to Lat Phrao to find a sexual partner. Compared to HIV negative MSM, HIV-positive MSM had less HIV testing: 31% had ever been tested for HIV, 12% had been tested in the past 6months; but were more likely to guess correctly their positive status (31%). Regarding psychosocial variables among HIV-positive MSM, 7% had regular methamphetamine use in the past 3months, 10% had >2 sources of discrimination, and 8% had >2 sources of discrimination due to being MSM. In multivariable model, age<30year old, self-identified as gay, had monthly income <50,000 baht ($1400 USD), had anal sex with men in past 12months, had >2 sources of discrimination because of being MSM, did not get HIV test in past 6months, and guess of positive HIV were significantly associated with HIV positive status. Young MSM with lower socioeconomic status (SES) should be prioritized for innovative approaches to promoting awareness and uptake of HIV testing. Societal stigmatization of MSM should be addressed as a potential barrier to uptake of voluntary HIV testing. Resilience factors among these marginalized MSM who still test frequently and remain HIV-negative despite residing in a context with community viral loads and discrimination should also be studied in order to curb the HIV epidemic in Bangkok.