Objectives: The purpose of this study was to determine the Influences on practical intention of Breast Self-Examination (BSE)in high school girls' knowledge and attitude about BSE. Methods: The participants were 208 high school girls from D city. Data were collected from August 7, to August 9 in 2013 by a questionnaire. Data were analyzed with SPSS/WIN 19.0 usingANOVA, one sample t-test, Pearson correlation, and stepwise multiple regression. Results: The factors influencing the practicalintention of BSE were attitude (ß=.370) and knowledge (ß=.138). The explanatory power of this model was 16.7%. Conclusions: The results of this study revealed that knowledge and positive attitude of BSE influenced on the practical intentionof BSE. Therefore, It is needed to develop the education program to obtain the knowledge and positive attitude of BSE forhigh school girls.