Background: Health professionals are expected to be competent in cardiopulmonary resuscitation (CPR), thus requiring acquisition and maintenance of knowledge and practice. If time is an important factor associated with the loss of these competencies, acting in CPR situations more frequently may contribute to greater retention. Thus, this study aimed to compare the retention of knowledge and skills in CPR among health professionals in clinical and intensive care after educational intervention. Methods: Intervention, prospective and analytical study. Nursing professionals from the clinical care unit (CCU) and intensive care unit (ICU) received a first theoretical and practical CPR training, called T1, and a retraining nine months later, called T2, being followed for a total period of 18 months. The comparison of the percentage score of knowledge and practice between the evaluations was made by the Wilcoxon test and Friedman's test, considered significant for p<0.05. Results: 56 professionals participated in all stages of the study, 34 CCU professionals and 22 ICU professionals. Soon after T1, the ICU group showed a greater ease of learning (p=0.032), which disappeared after T2, showing a leveling of the groups. Regarding skills, they also reduced with time in a similar way between groups. However, nine months after T2, even reducing practical skills, they were significantly higher in ICU professionals compared to those in the CCU (p=0.018). Knowledge retention nine months after T1 and T2 was similar between groups. However, nine months after T2 the ICU professionals were able to retain more practical skills in CPR (p=0.030). Conclusions: The retraining improved knowledge in both groups in a similar way, but the ICU group retained more practical skills, reinforcing the thesis that a higher frequency of action in CPR situations favors the retention of skills.