Objective: This study aimed to evaluate the effectiveness of the Immunization program against addictive drugs in Isfahan’s preschool centers.

Materials & Methods: To achieve the abovementioned objective, 60 children from preschool centers were selected through sampling. A quasi experimental pre-test post-test study was conducted. The Immunization Program (KADU packet) was administrated to the experimental group. The test used in this study was the ‘preschool children's knowledge, affects and behaviors toward addictive drugs’ checklist. Data were analyzed by Analysis of Covariance.

Results: According to the results, the Immunization program against addictive drugs in preschool children is effective.

Conclusion: The overall results of the study showed the Immunization program to be effective. It increased children's knowledge, changed their attitudes toward addictive drugs, and shaped avoidant and assertive behavior.