Adjusting the chronological age of preterm infants according to their gestational age is a widely accepted practice in the field of neurodevelopment. It has been suggested for the assessment of preterm infants with suspected infection, but has been poorly validated. Correcting for chronological age is especially critical in infants with a chronological age above 3 months, but a corrected age below 3 months due to the differences in assessment protocols. This study assessed the difference in incidence of serious bacterial infection (SBI) according to chronological and corrected age in preterm infants. A retrospective analysis of pediatric emergency department (PED) presentations was conducted for all 448 preterm infants born in between January 2010 and August 2019. Of the 448 preterm infants, 204 (46%) presented at one of 3 PEDs in Jerusalem, Israel, during their first year of life. Overall, 141 (31.4%) presented with fever and were included in the study. The infants were divided into 3 age groups: 1—corrected age >3 months; 2—chronological age >3 months, but corrected age <3 months; 3—chronological and corrected age <3 months. SBI was diagnosed in 2.6%, 16.7%, and 33.3% of the infants in groups 1, 2 and 3, respectively; (p< 0.01,p= 0.17,p< 0.001). The incidence of SBI in the control group of 300 term infants <3 months presenting to the PED due to fever was 15.3%. Preterm infants with a corrected age <3 months are at increased risk for SBI, similarly to term infants <3 months of age. Age correction should thus be considered for preterm infants presenting with fever.