This study evaluated the utilization of HIV voluntary counseling-and-testing (VCT) services targeting high-risk populations in Vietnam in order to inform decisions on program improvement and expansion. A total of 158,888 records collected from 55 VCT sites supported by the U.S. Centers for Disease Control and Prevention's Global AIDS Program in the period of 2002 to 2007 were used to analyze sociodemographic characteristics, risk exposures, seropositivity, test refusal, and failure to return for test results among VCT clients. High-risk exposures, such as injection drug use, commercial sex work, homosexual contacts or heterosexual contacts with high-risk sex partners, were reported in 126,815 (81%) records. Among high-risk clients, any condom use in the past month ranged from 34% to 71%. During the study period, 19% of the VCT encounters resulted in a positive HIV test; of those persons tested, 23% of men and 13% of women were HIV-positive. High HIV positivity rates were associated with injection drug use, being ill/recommended by health care provider, and having an HIV-infected sex partner. Of all records, 6.1% documented refusal of HIV testing. Failure to return for results was reported in 3.5% of records for clients who were tested. Previously testing positive was the strongest predictor of test refusal, and being referred by peer educators was associated with failure to return for results. The VCT program in Vietnam successfully targeted high-risk populations, and clients had high return rates using a standard testing strategy. Interventions to increase consistent condom use and promote access to prevention services among sex partners of high-risk individuals should be implemented and evaluated.