Purpose: Assuming that attitude education for basic cardiopulmonary resuscitation contributes to delaying the declining period, the purpose of this study was to determine retention of knowledge and performance after cardiopulmonary resuscitation (CPR) training. Method: Total 90-minute training consisting of a 30-minute lecture, a 30-minute practice by non-feedback mannequin (Actar 911 Squadron™; Vital Signs, New Jersey, USA), and a 30-minute attitude education (such as prevention of brain damage progression; confidence in ability to perform correct compression; understanding of damage caused by compression; ability to overcome the patient's appearance of distress; awareness of exemption from liability; confidence in the subject's physical capacity; low probability of infection) was conducted with 256 undergraduate students at Eulji University in accordance with 2015 AHA guidelines for layperson adult CPR. A self-assessing Likert scale (1, not at all; 2, not really; 3, undecided; 4, somewhat; 5, very much) was used before and after basic CPR training in three-month intervals (total of five times: March, May and September 2015, and December 2015, February and June 2016) to assess knowledge (how much you know about CPR) and performance (how much you can do CPR). Repeated measures ANOVA were used at α=.05 (2-side) of type I error rate to determine change in knowledge and performance scores over time. Findings: Statistically significant difference in knowledge (epsilon, .891) was found (p<.001), in which the Bonferroni method was applied as post hoc analysis. There was a difference in knowledge score between before-training and months three, six, and nine. However, no difference in knowledge scores between months three, six, and nine, implying that knowledge had been retained at least for nine months. Statistically significant difference in performance (epsilon, .831) was found (p<.001), in which the Bonferroni method was applied as post hoc analysis. There was difference in performance score between before-training and months three, six, and nine. However, no difference in performance score was found between months three, six, and nine, implying that performance had been retained at least for nine months. Applications: It was determined that knowledge and performance have been retained at least for nine month after basic CPR training combined with attitude education. Knowledge and performance scores that have improved compared to that before training were consistently maintained after training. Results of this study show lengthier retention than other studies, suggesting that attitude education added to basic CPR training delays decline of knowledge and performance. [ABSTRACT FROM AUTHOR]