OBJECTIVE:In our study, we aimed to investigate whether systemic inflammatory indices could be an indicator of mortality in very low birth weight (<1,500 g) preterm infants. METHODS: Very low birth weight preterm infants were included in our study, and patient data were recorded retrospectively. Neutrophil-to-lymphocyte ratio, platelet-to-lymphocyte ratio, monocyte-to-lymphocyte ratio, systemic immune-inflammation index, pan-immune-inflammation value, and systemic inflammation response index were calculated and recorded. The survivors and infants who died were compared for systemic inflammatory indices. RESULTS: A total of 1,243 very low birth weight infants were included in the study. Of the patients, 1,034 survived and 209 died. Neutrophil-tolymphocyte ratio, monocyte-to-lymphocyte ratio, platelet-to-lymphocyte ratio, pan-immune-inflammation value, systemic immune-inflammation index, and systemic inflammation response index were found to be statistically significantly lower in the mortality group than those in the survivor group (p=0. 039, p=0.001, p<0.001, p<0.001, p<0.001, and p=0.002, respectively). According to the receiver operating curve analysis, systemic immuneinflammation index with the highest area under the curve (0.844) was found to be the most effective systemic inflammatory indices in predicting mortality with a cutoff level of ≤28.87 (p=0.0001). Multiple regression analysis showed that a lower level of systemic immune-inflammation index (≤28.87) was independently associated with mortality (OR: 1.677, 95%CI 1.061-2.685, p=0.001). CONCLUSION: We have shown that low systemic immune-inflammation index value in very low birth weight preterm infants may be a novel systemic inflammatory index that can be used to predict mortality.