Respiratory viruses include rhinoviruses and enteroviruses (Picornaviridae), influenza viruses (Orthomyxoviridae), parainfluenza, metapneumoviruses and respiratory syncytial viruses (Paramyxoviridae), coronaviruses (Coronaviridae), and several adenoviruses. With the exception of adenoviruses, all possess an RNA genome. They are usually transmitted by direct hand to surface to hand contact and/or aerosol inhalation, and replicate in both upper and lower airways. Cellular and humoral immunity are both activated in response to respiratory viral infections as well as neural pathways, which contribute to distant inflammatory effects. Respiratory viruses are responsible for a wide variety of clinical syndromes including the common cold, acute otitis media, laryngitis, sinusitis, pneumonia, bronchiolitis, influenza, and exacerbations of asthma and chronic obstructive pulmonary disease. Diagnosis of respiratory viral infections is primarily clinical and is further supported by laboratory techniques such as antigen detection, culture, serology and more recently nucleic acid detection. Preventive strategies are based on avoidance of risk factors and vaccination when indicated. Treatment modalities include over-the-counter and non-specific remedies along with a small number of specific antiviral medications such as the influenza neuraminidase inhibitors.