T The increasing prevalence of smoking in developing countries including Indonesia causes the problem of cigarettes to become increasingly serious. Smoking is a way to be socially acceptable. So, some of those who smoke are caused by pressure from their peers. To reduce smokers can through health promotion about the dangers of smoking in various ways. Health promotion is essentially an activity or effort to convey a health message to adolescents or groups or individuals can obtain knowledge about better health. Sufficient knowledge will motivate individuals to behave well. Adequate knowledge about the dangers of smoking for health is expected to make people who have not smoked still not smoke and smokers who have already been able to stop this very dangerous habit. This study was conducted using the one-group pretest - posttest experimental design method. The study was conducted by comparing the knowledge and attitudes of respondents before and after the intervention with health promotion through posters. Respondents were nurjamilah junior high school students. The analysis of the results was done by calculating the normality of the respondents with the Kolmogorov-Smirnov test and analyzing the two variables with the Wilcoxon test. RESULTS Of the 120 respondents, the bivariate test results showed an attitude of having an abnormal distribution and knowledge had an abnormal distribution so that the Wilcoxon test was used in attitudes and knowledge with p = 0.000; (α <0.05) CONCLUSION This study shows the existence of health promotion through posters with smoking attitudes and knowledge in junior high school students.