This study aims to estimate the prevalence of having sex with FSW among males aged 15- 49, to describe some HIV-related behaviors among them and some correlated factors. The sample size included 1804 men in three cities, Hanoi, Da Nang and Can Tho in 2010. Of this sample, 6.9% of the sexually active men admitted that they ever had sexual relation with FSW. Only 27.6% of the men reported frequent use of condom and 52% used condom in the most recent sexual encounter with FSWs. The likelihood of having sex with FSW was higher in better-off men, those who were at higher educational level, those had two or more sexual partners during the last 12 months and those with experience of premarital sex. Program implementers as well as policy makers in the area of HIV prevention should pay more attention to the condom efficacy, condom use and related stigmatized issues.