Abstract : Critically ill children in the pediatric intensive care unit tend to be malnourished since admission or during treatment so they need to receive parenteral nutrition. The incidence of worsening liver function after parenteral nutrition is 60% but still limited data in children. Liver disease is often a mild and transient complication, but the condition may become progressive, irreversible, and fatal in patients receiving long-term parenteral feeding. The monitoring of aspartate transaminase (AST) and alanine transaminase (ALT) may be a preventive measure for hepatocellular injury. To analyze the increased levels of ALT and AST levels after parenteral nutrition in critically ill children. This research was a retrospective cross-sectional study to compare the differences in ALT and AST levels before and after parenteral nutrition in the pediatric intensive care unit (PICU) Haji Adam Malik hospital Medan, Indonesia. Data was taken from the medical record dated between July 2018 and July 2021. There were significant difference in both ALT and AST values before and after the administration of parenteral nutrition (p=0.0001). The results of AST values after parenteral nutrition showed an increase in the median AST after parenteral nutrition was 2 times the previous value. The mean value of ALT levels before parenteral nutrition was 19.28 ± 6.99 U/L and increased after administration was 42.45 ± 15.41 U/L. The results of ALT levels before and after parenteral nutrition showed p value = 0.001. Therefore, there was an increase in AST and ALT levels after parenteral nutrition. There were significant differences in ALT and AST levels between the before and after parenteral nutrition in critically ill children. There was a significant relationship between nutritional status and the increase in AST level, but not between ALT level.