Objective: The purpose of the present study was the meta-analysis of researches done on harm reduction and addiction treatment.

Materials & Methods: In this study, researches done on harm reduction and remedy were collected by the meta-analysis method. This was done using related keywords, searching the sites and theses of postgraduate studies. Finally, studies which were consistent with the criteria for inclusion in the meta-analysis were selected and desired information which were prepared by the author for testing the hypothesis with a negative questionnaire were extracted. Out of the 11 studies selected, the appropriate statistics to calculate effect size and other required information were recorded and the effect size as well as hypothesis analysis were calculated by CMA2 software.

Results: The results of this study show that identified independent variables on harm reduction and remedy have been effective. The value of combined effect size is 0.8 (d=0.8) and it is statistically considered significant. Since this value is in the range of 0.8 to 0.7, according to Cohen's classification, it is evaluated as average. Variables such as having a theoretical basis, the status of entry (New 6 months and more), the average of daily injection, integrated holistic therapy, medical interventions, quality of healthcare services, social esteem, methadone treatment and therapeutic interventions had statistically significant influence on harm reduction and remedy.

Conclusion: In order to achieve harm reduction and remedy, the status of entry (New 6 months and more), the average of daily injection, integrated holistic therapy, medical interventions, quality of healthcare services, social esteem, methadone treatment and therapeutic interventions related to nations must be considered.