Abstract Background: Neonatal sepsis is considered to be a systemic inflammatory response syndrome (SIRS) induced by bacteria, viruses, or fungi (yeast) infections. Neonatal sepsis is a major disease threatening the life of newborns, which is also one of the major challenges facing global public health. Aim of Study: To assess the ability of serum soluble form of triggering receptor expressed on myeloid cells-1 (sTREM-1) in predicting the diagnosis and prognosis of early and late onset neonatal sepsis in full term neonates. Patients and Methods: This cross sectional study that was conducted from 1/6/2022 to 1/1/2023 included 60 full term ne-onates in sepsis divided into 2 groups, group at day 1 of infec-tion, and group at day 4 of infection. Results: In our study serum soluble form of triggering re-ceptor expressed on myeloid cells-1 marker decreased at day 4 after antibiotics therapy and this is matched with GIBOT study. GIBOT study suggests that Post-therapy sTREM-1 levels were significantly decreased 48h after antibiotic intake in septic ne-onates compared to baseline levels. Thus, decreased sTREM-1 denotes favorable response and indicates that infection has been controlled. This implies a role of sTREM- 1 in monitoring response to therapy before getting culture results In our study sTREM marker was high in negative and positive blood cul-tures but higher in negative cultures. Our study shows that there was no statistically significant difference found in the level of total leucocytic count (TLC), hemoglobin and C-reactive pro-tein (CRP) from day 1 to day 4 respectively and also statistical-ly significant decrease in the level of alanine aminotransferase (ALT) in sepsis group than non sepsis group. Conclusion: sTREM marker was high in proved sepsis pa-tients by blood culture positive and suspected sepsis patients even blood culture negative than improved in the proven sepsis and suspected sepsis patients. Initial level of sTREM marker was higher than based level >5pg/mL. Used for follow-up at day 4 of infection. It was decreased at day 4 infection.