Section Editor: Prof. T.K. Partha Sarathy Introduction Acute respiratory infections (ARI) are a major cause of morbidity and mortality in young children worldwide. They account for nearly 3.9 million deaths every year globally. On an average a child has 5 to 8 attacks of ARI annually. ARI accounts for 30-40% of the hospital visits by children in office practice.ClassificationARI is classified based on the site of infection as Acute Upper Respiratory Infections (AURI) and Acute Lower Respiratory Infections (ALRI).AURI includes nasopharyngitis, pharyngotonsillitis and otitis.ALRI includes epiglottitis, laryngitis, laryngo tracheitisBronchitis, Bronchiolitis and pneumoniaAcute Upper Respiratory InfectionsInfections of the upper respiratory tract are very common in childhood. They constitute a major sector of the illness in Pediatric Office practice. Though mostly self limiting, they are a leading cause of morbidity like deafness and learning handicaps. Note: Beware of serious conditions like measles, mumps and diphtheria which may begin as nasopharyngitis. Blood stained nasal discharge especially unilateral, may indicate conditions like diphtheria or foreign body (old) and hence needs ENT evaluation. Sinusitis, serous otitis media or acute lower respiratory infections are common complications following nasopharyngitis. Clinically viral pharyngotonsillitis is indistinguishable from bacterial pharyngotonsillitis.