The present study aimed to investigate the effectiveness of motivational enhancement Therapy on Addiction treatment barriers and attitudinal ambivalence towards Addiction. This study is quasi-experimental research with a pretest-posttest control group design. The population included addicts who were referred to Addiction treatment centers in Rasht city in 2022. Seventy-four drug-addicted army conscripts were recruited by convenience sampling and were randomly assigned to two experimental and control groups. The Barriers to Treatment Inventory (BTI) and the Attitudinal Ambivalence Scale were used to measure views on Addiction treatment barriers and attitudinal ambivalence towards Addiction. Motivational enhancement Therapy was provided for the experimental group participants in nine sessions. In the end, the data analysis was done by multivariate analysis of covariance (MANCOVA) using SPSS.24 software. MANCOVA results indicated that motivational enhancement Therapy significantly affects views on barriers to treatment and attitudinal ambivalence towards Addiction (p < 0.001). Having motivation in any work can be effective, but if these motivations are not well managed and controlled, they bring many harms and dangers to the individual and the society. It should be acknowledged that motivational components play a very colorful role in the beginning, continuation, withdrawal, and return of Addiction. In this regard, investigating motivational interventions related to Addiction is of great importance