Early-onset neonatal sepsis (EOS) is observed in 1.7% of extremely preterm infants, with high morbidity and mortality rate. Cord blood procalcitonin (PCT) is a sensitive marker of EOS in full-term newborns, but it has been rarely studied in premature infants. The diagnostic value of cord blood PCT by immunofluorescence has been assessed as an early marker of EOS in a prospective cohort of extremely preterm infants, with a threshold at 0.5 μg/L. EOS was defined by a positive bacterial culture or by the association of postnatal biological/clinical signs of EOS and antibiotic treatment for more than 72 h. Correlation between PCT serum concentrations and postnatal morbidities was also analyzed. Among a total of 186 infants, 45 (24%) were classified as EOS. Blood PCT concentration was ≤ 0.5 μg/L in 114 infants, including 11 EOS (9.6%) and PCT was > 0.5 μg/L in 72 babies including 34 EOS (47.2%). PCT concentration > 0.5 μg/L was associated with higher risk of EOS (OR 2.18; CI95% 1.58-3.02; p < 0.0001). The receiver operating characteristic curve determined a cutoff of 0.7 μg/L as the best compromise, with an area under the curve of 0.75 (sensitivity 69%, specificity 70%). In multivariate analysis, clinical chorioamnionitis was associated with PCT concentration > 0.5 μg/L (OR 2.58; CI95% 1.35-4.94; p = 0.004). Cord blood PCT is a marker significantly associated with EOS in extremely preterm infants, but its sensitivity remains low. Its added value in combination with other early marker of EOS needs to be further investigated in this high-risk population.