Infections of the nasal cavity, sinuses, pharynx, epiglottis, and larynx are termed upper respiratory tracts infections. These include acute coryza, pertussis, sinusitis, pharyngitis, tonsillitis, epiglottitis, laryngitis, laryngotracheobronchitis, and influenza. Rhinoviruses and coronaviruses account for the majority of acute coryzal illnesses. Acute sinusitis (<4 weeks duration) is also usually viral in origin. About 70% of pharyngitis and tonsillitis cases are viral in etiology. Haemophilus influenzae (Type B) is responsible for most cases of epiglottitis. Acute laryngitis and laryngotracheobronchitis are usually caused by human parainfluenza viruses. This chapter focuses on upper respiratory tract infections, including their etiology, symptoms, demographics, natural history, complications, diagnosis, prognosis, and treatment.