<sec><title>Objectives</title><p>This study aimed to identify the effects of anti-smoking public service announcements on the attitudes of Korean college students toward smoking.</p></sec><sec><title>Methods</title><p>This study involved students via convenience sampling from seven universities who were randomly assigned to four groups. All groups completed a preliminary questionnaire, before being shown a public service announcement twice, and then completed a post viewing questionnaire.</p></sec><sec><title>Results</title><p>For announcements with positive messages, the proportion of changes in beliefs and attitudes were 39.1% and 19.8%, respectively, whereas those with negative messages showed a greater proportion of changes in the beliefs (59.7%) and attitudes (40.3%). After adjusting for sex and change in belief, the message types and smoking status were identified as factors affecting the change in the participants attitudes. A negative message resulted in a greater change in attitudes (odds ratio [OR], 3.047; 95% confidence interval [CI], 1.847–5.053). Ever-smokers including current smokers showed a greater positive change in attitude than never-smokers (OR, 6.965; 95% CI, 4.107–11.812).</p></sec><sec><title>Conclusion</title><p>This study found that positive anti-smoking public service announcements were more effective on attitude change than negative messages. Additionally these announcements were more effective among viewers who were current smokers or had a prior smoking experience.</p></sec>