Background: Neonatal sepsis is a major cause of morbidity and mortality in newborn. As the clinical manifestations are vague and non-specific, it is pertinent that an early detection is made to prevent serious morbidity and mortality. Neonatal sepsis is a clinical syndrome resulting from the pathophysiological effects of very severe bacterial infections that occur in the first month of life. Infection that occurs in the neonate can cause some changes in blood cells either erythrocytes, leukocytes, or platelet. The aim of this study was to determine the relationship between I/T ratio and leukocyte count in neonatal sepsis to accelerate the diagnostic process. Methods: The research methode used is analytic observational prospective study with cross sectional design, Research subjects are 103 neonates with sepsis which recorded on medical record from January 2013 to March 2017 at RS PKU Muhammadiyah Yogyakarta. Analysis of data used spearman correlation test to determine the relationship of I / T Ratio with leukocyte count in neonatal sepsis. Result: The results of the secondary data on 103 patients who had sepsis risk gained prevalence of neonatal sepsis based on onset, early onset sepsis is higher than the late onset sepsis (66.9%; 33.1%) by sex obtained group sex male is higher than the female gender group (58.3%; 41.7%). BBLC is higher than BBLR (67%;33%). There were 5 patients septic neonates with I/T ratio ≥0,2 with leukocytosis and there is no patients with I/T ratio ≥0,2 with leukopenia. Spearman correlation analysis showed a significant correlation between I / T ratio with leukocyte count p = 0.005. Conclusion: Correlation coefficient resulted in this study between I/T ratio and leukocyte count is r=0.277 and p<0.05 (0.005). In Conclusion, There was a correlation between levels of leucocytes count with leukocyte count in neonatal sepsis patients in RS PKU Muhammadiyah Yogyakarta.