Purpose: The purpose of the study was to analyze the nursing activities related to continuous renal replacement therapy (CRRT) in the intensive care units (ICU). Methods: We developed a list of 31 CRRT related nursing activities based on literature review and reviewed by expert group. A total of 109 direct time measurement records by 43 ICU nurses were collected and analyzed in terms of total time per shift, frequency, standard time, difficulty and performance levels of each CRRT nursing activity. Results: The mean time for CRRT nursing activity was 85.60 minutes per 8 hour shift. Nurses have spent average $9.46{pm}6.98$ minutes in a shift for "waste fluid bag change" activity. In addition, "check catheter location" was the most time consuming single activity. The most difficult activity was "counseling-answer" and the most competent one was "dialysis solutions change". Conclusion: The CRRT nursing activities accounted for a significant portion of total nursing workload. Practical allocation of nursing staff for CRRT patient along with development of a new nursing cost system need to be considered. Continuous nursing educational and training programs on CRRT should be developed.