Purpose: This study was performed to investigate the level of knowledge, self-confidence, and intention of basic life support (BLS) and identify the reason why clinical nurses lack confidence to initiate BLS at the cardiac arrest scene. Method: A cross-sectional survey was used with questionnaires which authors developed; a BLS knowledge questionnaire and a tool for measuring the level of self-confidence and intention of performing BLS. The subjects consisted of 396 nurses by convenient sampling from ten small to medium sized hospitals in Korea. Data were collected from March to August, 2008. Data were analyzed by the SPSS/WIN 14.0 program with t-test, ANOVA, and Pearson correlation coefficients. Results: The percentile score of BLS knowledge was 40.6%, self-confidence 62.1%, and intention 73.0%. Clinical career rather than BLS knowledge has a significant effect on increasing the self-confidence and intention of performing BLS. A major reason for not performing BLS was lack of confidence in operating an AED (automatic external defibrillator). Conclusion: An effective and continuous training program especially including AED for CPR should be provided with clinical nurses to increase self-confidence and intention of performing BLS and to improve the survival of cardiac arrest patients in the hospital.