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Background: community-acquired pneumonia (CAP) is one of the most common pediatric diseases. Early and accurate diagnosis of CAP in children has a great value in avoiding pneumonia complications and decreasing rates of pneumonia related mortality. Aim of the work:this study aims to investigate the role of procalcitonin (PCT), C-reactive protein (CRP) and white blood cells (WBCs) count in diagnosis of childhood CAP. Patients and Methods: 90 infants and children aged from 2 months to 5 years (60 months) were included in this study. They were divided into two groups group I: 60 patients hospitalized for CAP and group II: 30, age and sex matched, healthy controls attending the outpatient clinics of the same hospitals for routine care. Chest x-ray was performed to the patients group only, while WBCs count, serum CRP, serum procalcitonin were applied to both patients and controls. Results: WBCs count, neutrophil percentage, CRP level, procalcitonin concentration were higher in the patients group than the controls with high statistically significant difference (13.4±3.4 vs 8.3±1.7) (54.5±15.4 vs 37.2±6.7) (57.5±30.1 vs 5.7±5.6) (0.5±0.47 vs 0.07±0.04) respectively. Using the AUROC test WBCs count at cut-off value >10.5 x10³ cell/mm³, CRP at cut-off value >20 mg/L, procalcitonin at cut-off value >0.17 ng/ml could predict presence of CAP in the patients with 83.3%, 85%, 86.7% sensitivity and 76.6%, 100%, 96.7% specificity respectively. Conclusion: evaluation of WBCs count, serum CRP and serum procalcitonin concentration has an important role in diagnosis of CAP in infants and children.