The aim: 1. To assess the existing knowledge of high-school students regarding drug addiction. 2. To measure the effectiveness of planned teaching program upon study groups knowledge on drug addiction. 3. To assess and compare the knowledge levels among participants (post-test) for both groups (study and control). 4. To find the association between studies group post-test levels of knowledge with participants socio-demographic variables. Materials and methods: The present study carried out by using quasi-experimental design with two groups and over three assessment phases, in period from September 2019 to July 2021, with objective of assessing educational program effectiveness in improving knowledge of drug addiction among students at high-school in Al Najaf city. Total of 70 high-school students divided into two groups, which were included by non-probability purposive sampling methods. Results: After conducting program the (post-tests) revealed significant improvement in knowledge of students from study group in comparing to control group, which remained at same level of knowledge toward drug addiction with mild decline. Conclusions: Furthermore, the study concluded that the education program was effective in enhancing knowledge of students concerning drug addiction. Besides, it is beneficial to conduct such programs in order to protect students from addiction risk. The study recommended for further modification and application of current program in future besides the need to educate teachers and as well as families toward drug addiction issue.