Background <p>While C-reactive protein (CRP) is a commonly used sepsis biomarker in neonates, studies in older patients propose procalcitonin (PCT) as potentially superior due to earlier rise in response to bacterial infection and shorter half-life.</p> Methods <p>We conducted a prospective cohort study of VLBW infants undergoing sepsis evaluations at a level IV neonatal intensive care unit (NICU) and combined the analysis with a retrospective data review from a different level III NICU. We adjusted all analyses for study site to account for potential heterogeneity. Two blood samples for each biomarker obtained within a 24-h period were analyzed. Diagnostic accuracy was assessed by sensitivity, specificity, predictive values, likelihood ratios, and the area under the receiver operating characteristic (ROC) curve (AUC).</p> Results <p>At literature-defined cut-offs, PCT demonstrated higher sensitivity, but lower specificity for sepsis compared to CRP. Using ROC-optimized cut-offs, CRP showed increased specificity (85%) but lower sensitivity (48%), whereas PCT maintained relatively high sensitivity (73%) but even lower specificity (60%). In multivariable modeling, only CRP was significantly associated with sepsis. Correlation between the biomarkers was weak.</p> Conclusions <p>PCT did not outperform CRP as a sepsis biomarker. CRP was more specific and remained the stronger independent predictor of sepsis.</p> Impact <p><UnorderedList Mark="Bullet"> <ItemContent> <p>Procalcitonin (PCT) shows higher sensitivity, but lower specificity compared to C-reactive protein (CRP) in very low birth weight infants with sepsis.</p> </ItemContent> <ItemContent> <p>CRP emerges as the stronger independent predictor of sepsis in multivariable models.</p> </ItemContent> <ItemContent> <p>This study constitutes one of the largest United States cohorts directly comparing CRP and PCT in this high-risk group.</p> </ItemContent> </UnorderedList></p>