Purpose: The purpose of this study was to explore the knowledge of, attitude toward, and intention to use Emergency Contraceptive Pills (ECPs) and their relationships among Korean high school girls. Methods: This study is a cross-sectional correlational survey. Data were collected from 191 high school girls by self-report questionnaires from December 10 to 22, 2008. Result: The mean scores of knowledge, attitude, and intention were 4.74 (range 1 to 12), 2.60 (range 1 to 5), and 3.36 (range 1 to 5) respectively. Only 45% of participants had received education on ECPs and most respondents (77.5%) wanted to know more about it. Participants who had a more positive attitude toward ECPs had a greater intention to use it. Participants who had received education on ECPs had more knowledge than those who had not received education. However, there were no differences in attitude or intention between groups. Conclusion: This study indicates that efforts should be made to provide education on ECPs to high school girls to increase awareness and to minimize the misuse of ECPs. Also, educational programs should be designed to improve knowledge as well as promote a more positive attitude toward ECPs.