OBJECTIVE Continuous renal replacement therapy (CRRT) is becoming the treatment of choice for supporting critically ill pediatric patients. However, a few studies present have reported CRRT use and outcome in neonates weighing less than 3 kg. The aim of this study is to describe the clinical application, outcome, and complications of CRRT in small neonates. METHODS A retrospective review was performed in 8 neonatal patients who underwent at least 24 hours of pumped venovenous CRRT at the Samsung Medical Center in Seoul, Korea, between March 2007 and July 2010. Data, including demographic characteristics, diagnosis, vital signs, medications, laboratory, and CRRT parameters were recorded. RESULTS The data of 8 patients were analyzed. At the initiation of CRRT, the median age was 5 days (corrected age, 38(+2) weeks to 23 days), and the median body weight was 2.73 kg (range, 2.60 to 2.98 kg). Sixty-two patient-days of therapy were reviewed; the median time for CRRT in each patient was 7.8 days (range, 1 to 37 days). Adverse events included electrolyte disturbances, catheter-related complications, and CRRT-related hypotension. The mean circuit functional survival was 13.9±8.6 hours. Overall, 4 patients (50%) survived; the other 4 patients, who developed multiorgan dysfunction syndrome, died. CONCLUSIONS The complications of CRRT in newborns are relatively high. However, the results of this study suggest that venovenous CRRT is feasible and effective in neonates weighing less than 3 kg under elaborate supportive care. Furthermore, for using potential benefit of CRRT in neonates, efforts are required for prolonging filter survival.