Background & Objectives : This study was prepared to determine the frequency of Staphylococus aureus nasal colonization among intravenous drug abusers with respect to this fact that the rate of colonization is dependent on various factor including addiction behaviours. There wasn't any native study on this subject. The purpose of this study was to prepare the basic data of S.aureus nasal colonization among intervenous drug abusers, in order to reducing the incidence and nasal carriage rates of S.aureus infections.

  Methods : This was a prospective cross sectional study that included all of intravenous drug abusers who referred to three hospitals of Tehran from 2005 to 2006. Specimens for culture were obtained by swabbing anterior nares. Swabs were inoculated into nasal chapman broth and incubated at 35 °C for 48 hours. Isolated colonies were further subjected to identification and antimicrobial susceptibility testing. The related data were collected using patients` medical files and analyzed with using SPSS 11.

  Results : Staphylococcus aureus was grown i n 38 cultures (26.2%). We did not find any significant relationship between variables such as, economic condition, methods of using drugs, frequency of drug use, infection with different viruses, gender and colonization by Staphylococcus aureus.

  Conclusion: We observed lower nasal colonization with Staphylococcus aureus among patients. We suggest preparing similar study in order to clarify the role of different factors that have effect on the rate of nasal colonization with Staphylococcus aureus.