The cross-sectional descriptive study was done on 400 injection drug users (IDUs) in 02 methadone treatment centers in Hanoi city. The study results show that: average initial dose for patients participating in the study is 20,6 mg/day
average maintenance dose is 69,7mg/day. The frequency of daily heroin use of patients is considerably reduced: pretreatment frequency is 2,86 times/day, dose-finding trial frequency after 7 days is 1,30 times/day, after 30 days: 0,33 times/day, after 3 months: 0,21 time/day. The rate of patients being transferred to other health services: clean needle provision is 18,5 percent
voluntary counseling test is 19,0 percent. These are preventive intervention in order to reduce HIV prevalence among injection drug users.