This study examines the risk factors related to HIV infection among 400 female sex workers (FSWs) aged 16-57 years in Vinh Long Proovince, Viet Nam. It uses secondary data from a cross-sectional study about knowledge, attitude, beliefs, and practice on HIV/AIDS. The main purpose is to determine the impacts of risk factors on HIV infection. Binary logistic regression showed perception of risk, perceived pay value, and using drug were significantly associated with HIV infection. FSWs who used drug were 32 times more likely to be infected with HIV than their counterparts. FSWs who reported that they had high risk of HIV infection were more likely to be infected with HIV than the ones reported that they had low risk or no risk of HIV infection. In addition, low income FSWs were more likely to be infected with HIV than high income FSWs. The findings suggested setting up a Drop-in-Center for FSWs who come to share both difficulties and experiences to protect themselves from HIV infection. Furthermore, strengthening the peer educators’ channels to provide HIV/AIDS information, knowledge, living skills and condom, needles and syringes directly to FSWs is strongly recommended.