This cross-sectional survey examines the utilization of HIV care and treatment services after HIV diagnosis among women in Vietnam and describes factors that may be associated with failure in seeking services. From May 2007 to November 2007, we conducted structured interviews with 353 HIV-positive women living a Haiphong, a northern province of Vietnam. The women were recruited through a network of people living with HIV/AIDS (HPN+) by means of snowball sampling and through the local, governmental HIV registration system (Provincial AIDS Centre [PAC]). Approximately 26.3% of the study participants had never attended HIV care and treatment services. Failure in seeking the services was associated with not being registered in the PAC (odds ratio [OR]: 3.0; 95% confidence interval [CI]: 1.4–6.4), not having a known HIV-positive family member (OR: 3.2; 95% CI: 1.2–8.3), not having disclosed HIV status (OR: 4.0; 95% CI: 2.0–8.1), and factors associated with the testing situation, whereby women who were tested by chance had a 4.0 times increased OR (95% CI: 1.4–11.7) and women who were tested in relation to antenatal care or delivery had 3.0 times increased OR (95% CI: 1.1–8.5) for failure to seek HIV care compared to women who had been tested because their husbands/partners were sick or had died. We suggest that the posttest counseling and referral system for HIV care and treatment need to be improved. An alternative system for picking up those not wishing to attend the official system might help to approach these needy women.