Purpose: This study was undertaken to test effects of action oriented BSE education on knowledge, selfefficacy, and performance competence in nursing students. Methods: A non-equivalent pre-posttest of time serial quasi-experimental design was used to prevent diffusion of the experiment. Out of 53 nursing students selected by convenient sampling in the third grade at a nursing college, 27 students were randomly assigned to the control group and were first given a traditional lecture on BSE. For the experimental group of 26 students action oriented BSE education consisted of lectures, demonstrations with breast models, and BSE skill practice by micro teaching. Results: There was no significant difference in general and BSE-related characteristics between the two groups. Scores of the experimental group in knowledge, self-efficacy, and performance after the intervention were significantly higher than those of the control group. Conclusions: Results showed that action- oriented BSE education was effective in increasing knowledge, self-efficacy and performance competence in nursing students. Education for students should incorporate strategies reinforcing confidence by practicing actual BSE skills as well as acquiring knowledge of BSE, so that students can become competent and practical cancer prevention educators.