"Background: NT-proB-type Natriuretic Peptide (BNP) (NT-pro BNP) is one of the biomarkers that has been studied in recent decades in connection with pediatric heart failure (HF) and congenital heart disease (CHD). Recently, infants hypothesized that serum. NT-pro BNP levels might be a good predictor of septicemia severity and response to treatment and prognosis in these patients. This study investigated the relationship between serum natriuretic type B peptide level and neonatal sepsis. Materials and Method: In this case-control study, all full-term and pre-term neonates admitted to children’s Hospital, TabrizIran(2021), with sepsis and a septicemia diagnosis were confirmed after obtaining consent. The study was deliberately entered by the patient's parents or legal guardian. Complete Blood Count with Differential (CBC/Diff ), C - reactive protein (CRP) , Bacterial Culture (B/C) , Urine Analyze(U/A),Urine Culture (U/C) ,NT-pro BNP were checked and finally compared with laboratory results of the same number of infants who did not have clinical and laboratory symptoms of sepsis. After collecting samples, laboratory results, including serum levels of NT-pro BNP, were compared in case and control groups. Results: One hundred patients were studied in two groups. Thirty-eight patients (38%) were boys, and 62 patients (62%) were girls. The mean age of the patients was 7.58±7.46 days. The mean weight of the studied patients was 2811.80±620.33 grams, with a median of 2855 grams. The most common clinical symptom observed in patients in the case group was fever (100%) followed by Poor feeding (84%). In the control group, all patients had jaundice. Neonates with sepsis had significantly higher initial pro-BNP values than the control group (10023.80 vs. 2247.20; p=0.001). The NT-pro BNP level cut-off point in predicting the final treatment status and mortality of neonates with sepsis was 9583 pg/ml with 97.7% sensitivity and 93.6% specificity. Conclusion: Measurement of serum level of NT-Pro BNP in neonates with sepsis at the time of clinical signs with 97.7% sensitivity and 93.6% specificity with a cut-off point of 9583 is an important prognostic factor in the therapeutic management of patients."