Background: Community acquired pneumonia (CAP) is defined as the presence of signs and symptoms of pneumonia in a previously healthy child due to an infection which has been acquired outside hospital. This study aimed to evaluate the value of Pentraxin-3 (PTX-3) as a clinical marker in diagnosis of CAP in pediatrics and assessment of its severity. Methods: This cross-sectional study included 60 children, divided into 40 children with CAP and 20 age and sex-matched healthy controls. All patients underwent clinical and chest examination, laboratory investigations, and radiological examination. Results: The PTX3 levels showed statistically significant positive correlation with the WBCs count (r = 0.285, p = 0.027), neutrophils count (r = 0.259, p= 0.046), ESR (r = 0.486, p < 0.001), hospital stay length (r = 0.465, p = 0.003), CRP (r = 0.365, p = 0.004), and PCT (r = 0.372, p = 0.003). PTX3 level of 7.94 (ng/ml) wase able to differentiate patients with CAP from the control group with a sensitivity of 95% and a specificity of 95%. PTX3 had significantly higher diagnostic performance for discrimination of CAP cases compared to CRP (p =0.041) and PCT (0.03). Conclusion: PTX-3 emerges as a promising biomarker for CAP diagnosis and severity assessment, exhibiting potential advantages over conventional markers like CRP and PCT. The findings highlight the clinical utility of PTX-3 in discriminating CAP cases from controls with high sensitivity and specificity.