Background: Pneumonia and other lower respiratory tract infections are the most leading causes of death worldwide. Pneumonia is common and is associated with significant morbidity and mortality between children. Good and early diagnosis is a very important factor to avoid severe complications and drawbacks, and proper management of patients is vital in the prognosis of pneumonia. Although in the developed world the diagnosis depends mainly on the radiographic findings, but the World Health Organization has classified and defined pneumonia subjected to the clinical findings found by visual inspection and on the timing of the respiratory rate. The aim of this review: is to evaluate the indicators of pneumonia severity in children under-five years of age. Conclusion: Pneumonia in children is related to significant morbidity and mortality; however, data are limited in predicting which children will have negative outcomes, including clinical deterioration, severe disease, or development of complications