Objectives: identify the rate of adherence in HIV/AIDS patients on ART and the associated factors. Method: Design cross-sectional descriptive study, 124 HIV/AIDS patients on ART enrolled from 9/2005-l2/2007 at Ngo Quyen OPC. Identify the adherence and the associated factors through physician assessment and self-assessment questionnaire. Results: The rate of good adherence is 87.9 percent. No difference of the rate of good adherence between no-IDU and IDU - Injected Drug Users (90.6 percent and 83.6 percent) p 0.05, OR = 1.898
(95 percent CI:1.308 to 4.282). The associated factors to the adherence such as: a stable job, join the peers clubs, OIs during treatment. Conclusions: Good adherence is 87.9 percent, needs to be improved in order to get effective treatment and prevention of drug resistance. Patients with stable jobs and join the club peers, family support, will mantain good ahdrence. Patients with opportunities infections should be enhanced support. Injected drugs users do not affect to ahrence.