Abstract
Objective: To determine the effectiveness of the education program on high school mal students' knowledge about substance use.
Methodology: A quasi-experimental design was carried out at Al-Kut city, Iraq from 20 September to 24 November 2022. The study included 60 Al Kut Education Directorate students using non-probability (purposive) sampling. Direct interview utilizing a specialized questionnaire with two parts (59) items was used. Part 1 had 8 socio-demographic items and Part 2 had 51 items on substance use knowledge. SPSS was used to examine data. Inferential statistical data analysis, T-test and ANOVA were used to analyze socio-demographic factors and student knowledge.
Results: There was a highly significant difference through periods (Pre-test, Post-test I and Post-test II) for the study group regarding students’ knowledge about substance use that indicate the effectiveness of educational program (p≤0.05).
Conclusion: The program was effective in improving high-school students’ knowledge about substance use and there was a significant difference in knowledge between students who attended the program sessions (study group) comparing to those who not attended program sessions (control group).

Key words: Effect, students' knowledge, educational program, substance use.