The research objective was to determine the effect of health education with audio-visual media on the level of student's knowledge about the dangers of smoking.

The research used a pre-experimental design with The One-Group Pretest and Posttest approach. Data collection was using a questionnaire about the dangers of smoking. The sample in this research were male students of VII and VIII grade. The total sample size of this research is 77 people. Data analysis is used as one group t-test.

The results showed that the mean level of student's knowledge about the dangers of smoking before being given treatment was 51.8%. After that, the mean level of student's knowledge about the dangers of smoking after being given treatment was 71.9%. The result of p-value = 0.000, which means that there is an effect of health education with audio-visual media on the level of student's knowledge about the dangers of smoking. Suggestions, that can be used as material in counseling and add information in order to increase student knowledge about the adverse effects caused by smoking and to increase extra-curricular activities in school, so that students can be a focus on positive activities and avoid bad behavior to smoke.