This study evaluated the diagnostic and predictive utility of cerebrospinal fluid (CSF) white blood cell (WBC) components in the diagnosis of bacterial meningitis in infants discharged from the neonatal intensive care unit (NICU). No single clinical prediction rule had the optimal discriminatory power for predicting culture-proven bacterial meningitis, and clinicians should be cautious when interpreting CSF WBC parameters in infants with suspected meningitis.