More and more it is spoken about this morbid association between asthma and allergic rhinitis; this two diseases are interconnected but were often distinctly approached over time. Anyway, they share interesting pathogenic and therapeutic features. The current article reviews epidemiologic data, pathogenic mechanisms, common actions as well as common elements coming from experimental medicine, everything pleading for a new concept, "one airway" or "Combined Allergic Rhinitis and Asthma Syndrome". From here we can also draw conclusions marking new therapeutic directions where anti- leukotrienes often prove to be useful.
