Abstract (provisional): Background: The severity of HIV/AIDS pandemic linked to injecting drug use is one of the most worrying medical and social problems throughout the world in recent years. Myanmar has one of the highest prevalence rates of HIV among the IDUs in the region. Aim The objective of the study was to determine the risk behaviours among HIV positive injecting drug users in Myanmar... Methods: A non matched case control study was conducted among 217 respondents registered with a non governmental organization's harm reduction center. 78 HIV positive IDUs were used as cases and 139 non HIV positive IDUs as controls. The study was conducted between April-May 2009. Data was analysed using SPSS version 15 and the study was ethically conducted... Results: Factors like age, marital status, age first used drugs, drug use expenditure, reason for drug use, age first used injection were found to be significant. Other risk factors found significantly associated with HIV among IDU were education (OR 2.3), location of respondent (OR 2.4) type of syringe first used (OR 5.1), sharing syringe at the first injection (OR 4.5) and failure of drug detoxification programme (OR 4.9). More HIV positive IDUs were returning used syringes in the centre (OR 3.3)... Conclusions: Prudent measures such as access to sterile syringes and continuous health education programmes among IDUs and their sexual partners are required to reduce high risk behaviours of IDUs in Myanmar.