Background: Iran has a concentrated HIV epidemic among people who inject drugs (PWID). Low HIV testing uptake could contribute to the significant number HIV-infected PWID, who go undiagnosed. This study aims to assess HIV testing uptake and its correlates among PWID in Iran. Methods: Data were collected through a national cross-sectional bio-behavioral study in 2010. Adult male HIV-negative PWID were included in the current analysis. All estimates were adjusted for the clustering effect of the sampling sites. Multivariable logistic regression was used to examine the correlates of recent HIV testing and adjusted odds ratios (AOR) were reported. Results: Out of the 2146 eligible PWID for this study, 49.8% reported having ever tested for HIV. However, only 24.9% had tested in the previous year and received their test results. Around 65.2% of PWID knew an HIV testing site. In the multivariable analysis, knowing an HIV testing site (AOR. = 13.9; P-value.