Although influenza is generally seen as an important cause of excess mortality in patients with asthma or chronic obstructive pulmonary disease (COPD), this mortality is nearly exclusively present in patients over the age of 60. Morbidity in patients with asthma or COPD is related to respiratory infections, including influenza. Vaccination against influenza has proven to be effective in nursing home populations, decreasing both mortality and morbidity during epidemics of influenza A. In younger patients with asthma or COPD, however, the effect of vaccination is more ambiguous. Exacerbation of respiratory disease is not due to influenza vaccination (except in allergy to chicken protein), from which we can conclude that influenza vaccination is a safe method to prevent a potentially serious respiratory infection in patients with asthma or COPD.