The aim of this study was to evaluate diagnostic value of 25-hydroxyvitamin D level, Upar, IL-33 and ST2 in comparison with C-reactive protein, TNF-alpha and Interleukin-6 in neonatal sepsis. A total of 106 term babies were included 20 of whom were the control group. We used only data of high probable sepsis with blood culture positive infants, therefore 46 infants were excluded. Blood was collected from infants from the first day of sepsis (1.value) and 48-72 hours later (2.value). There were significant differences between the controls and sepsis (1.value) for 25-hydroxyvitamin D levels (35 +/- 19ng/ml and 69 +/- 7.5ng/ml, p=0.01), for IL-33 levels (90 +/- 34 ng/ml and 412 +/- 170 ng/ml, p=0.01), for sST2 levels (453 +/- 44 ng/ml and 4120 +/- 2720ng/ml, p=0.01), for sUpar levels (2.1 +/- 1.3 ng/ml and 11.4 +/- 5.2 ng/ml, p=0.01), respectively. There were significant differences between sepsis (1.value) and sepsis (2.value.) with reference to 25-hydroxyvitamin D, IL-33, sST2, and suPAR levels, respectively. In the light of these results, it may be suggested that 25-hydroxyvitamin D level, upar, IL-33 and ST2 can be used as an acute phase reactant like C-reactive protein, TNF-alpha and Interleukin-6 in diagnosis of neonatal sepsis.