Background: Sepsis is one of the main causes of death among children even in developed countries. Many studies have shown increased serial blood lactate level measurements to be associated with increased risk of sepsis mortality. In this study we aimed to evaluate the correlation of plasma bicarbonate and lactate plasma on the severity of sepsis in pediatric patients. Method: This retrospective study was conducted in Hasan Sadikin General Hospital, Bandung, West Java in Januari – April 2019. Bivariable analysis aimed at assessing the correlation between HCO3 and lactate against PELOD scores using Spearman rank correlation. Data were tested descriptively and data analysis was carried out using the Statistical Product and Service Solution (SPSS). Result: From January 2018 through December 2019, 80 patients ( 46 boys [57.5%] and 34 girls [42.5%]; mean age 26 months) were included in the study analysis. Thirty-eight percent of subjects had normal lactate levels <2 mmol / L before received fluid resuscitation. At 1 hour and 6 hours after resuscitation, lactate levels tend to decrease. At 1 hour and 6 hours after fluid resuscitation, bicarbonate levels tend to increase. Discussion: This study is a correlational analytic study with a retrospective design measuring the correlation between levels of lactate and bicarbonate with the severity of the disease based on the PELOD-2 score of septic children. In this study, it can be concluded that there were no correlation between bicarbonate, lactate serum with severity of sepsis in pediatric patients based on PELOD-2 scoring system. However there’s a significant negative correlation between bicarbonate level and serum lactate.