Background: high Procalcitonin (pro-CT) plasma concentrations(> 9-10 μg/l), following cytokines release, seem to be an early marker of severe Bacterial Infections (BI). Lower concentrations are found in viral infections. We evaluated early pro-CT concentrations in course of severe pediatric BI. Subjects: 12 children (5′ days-16 years); diagnosis of sepsis, septic shock and bacterial meningitis (positive blood and/or CSF cultures). Interventions: pro-CT (ImmunoLuminescent Assay), CRP, interleukin-6 (IL6) and tumour necrosis factor α(TNFα) (ELISA) were measured on admission. Results: pro-CT concentrations were above 10 μg/l in all but 2 children (16,6%): a 1 month old girl (S. Virchow meningitis, pro-CT 0,36 μg/l, CRP 145 mg/l, IL6 14 pg/ml, TNFα <13 pg/ml) and a 6 month old boy (H. Influenzae meningitis, pro-CT 4,4 μg/l, CRP 103 mg/l, IL6 20 pg/ml, TNFα < 13 pg/ml). In both pro-CT concentrations remained low and CRP rapidly fell below 10 mg/l under antibiotic treatment. Conclusions: we speculate that pro-CT concentrations can fail to rise above 10 μg/l in a number of bacterial meningitis maybe due to low bacterial concentrations.