Objective: To describe sexual risk in Vietnamese men who have sex with female sex workers by describing the prevalence of sexual risk behaviours among Vietnamese men living in inner Sydney and comparing this prevalence with national data. Method: Telephone interviews were completed with a random sample of 499 Vietnamese men, selected from the electronic telephone book using a list of common Vietnamese surnames. Results: Of the 761 eligible men contacted, data were obtained from 499 men, giving a response rate of 66%. 20% reported having had sex with a sex worker, including 12% of Vietnamese men who had had sex with a sex worker outside Australia, predominantly in Vietnam. Of the men who had had sex with a sex worker in the past year, 28% had unprotected vaginal or anal sex at their most recent commercial sexual encounter. Ever having paid for sex was significantly associated with a higher lifetime number of sexual partners (p<0.001), history of a sexually transmitted infection (p<0.001) and ever having an HIV test. 1% of respondents reported injecting non-prescription drugs. Less than 1% said they had had sex with another man. Conclusion: Vietnamese men living in Sydney generally show lower levels of sexual and related risk behaviours than other Australian men. However, sex with a sex worker is common among Vietnamese men in Sydney and also when they travel outside Australia. Unprotected vaginal sex with sex workers is surprisingly common. Programmes are needed to deal with vulnerabilities in these areas.