This study examined predictors of HIV testing, successful condom negotiation with clients, and self-reported sexually transmitted infections (STIs) among Vietnamese female sex workers (FSW). Data were collected by using face-to-face interviews from a community sample of 610 FSW from Nha Trang city during October-December, 2000. Having had an HIV test was associated with having spent time in a rehabilitation center. Consistently successful negotiation of condom use occurred most among FSW who had few clients, understood how HIV was not transmitted, and had not reported ever having any symptoms of STIs. Migration to Nha Trang for sex work was a risk factor for an STI diagnosis; successful negotiation of condom use had a protective effect. Our results suggest the need for voluntary HIV counseling and testing, further promotion of condom use among FSW populations, and better use of rehabilitation sites to promote HIV prevention.