Aim: In the last decade, the prevalence of injecting drugs has been increasing rapidly. Injecting drug use puts one at the risk of risky behaviors that affect the health of individual and society. The present study aims at evaluating and comparing risky behaviors of injecting and non-injecting drug users. Methods: In this cross-sectional descriptive study, 4400 addicts referred to public, private and drop-in-centers (DICs) in 2014 were enrolled. The addicts were divided into injecting and non-injecting drug users. A researcher-made questionnaire was used to collect demographic data and the pattern of drug use and risky behavior. Data were analyzed by SPSSV21, chi-square test and ANOVA. A significance level of less than 0.05 was considered. Results: Among the addicts, 4% were injecting drug users (IDUs) and 96% non-injecting drug addicts (non-IDUs). The age of the first injection was 24.68 ± 6.45 years old. The age of onset of drug use in IDUs was significantly lower than in non-IDUs (P<0.001). Risky behaviors including the use of shared needles, risky sexual relations, a history of sexually transmitted infections and a history of imprisonment and suicide were significantly higher in IDUs. Addiction relapse and slip during treatment were higher in IDUs (P<0.001). Conclusion: Injecting drug addiction significantly increases the risk of relapse and risky behaviors. Priority should be given to risky behavior prevention programs.