Purpose: The effectiveness of teaching cardiopulmonary resuscitation (CPR) in schools is known to be higher among older students. However, several easier programs have been successful even for primary school children. The purpose of this study is to determine the optimal target age for teaching CPR in schools. Methods: Six classes from the fifth to the tenth grade were randomly selected. A video-based self-instructional program was presented by health teachers in each school using the Korean version of CPR Anytime(TM) during normal school hours. Questionnaires were given after training to determine their degree of confidence in performing CPR, their willingness to perform CPR on a family, a friend, and a stranger, and at what age the children wanted to learn CPR. Skill tests were administered for several volunteer students. One week after the training, the students were asked to what extent they had shared their knowledge of CPR technique with other people. Results: Two hundred one students were given the CPR instruction. The confidence in performing CPR was lowest among seventh grade children. The willingness expressed by the students to perform CPR on a family member, a friend, and a stranger were 99.5%, 95.7% and 58.8%, respectively, with boys in the tenth grade most willing to perform CPR on a stranger. The students responded that it is most suitable to learn CPR at grade 6.4±2.4. The highest average skill score of 9.5/11 was for sixth grade. The average distribution rate was 1.23, and again this was highest in sixth grade at 3.72. Conclusion: This study suggests that the optimal target school age for CPR education using video-based self instruction may be at approximately the sixth grade.