The immunologic reaction to fungal stimuli has long been thought to be a contributor to the development of sinonasal disease. We aim to review the role of fungi in upper and lower airway inflammatory diseases. The immune response to fungi in the pathogenicity of specific respiratory inflammatory diseases such as allergic bronchopulmonary aspergillosis and a subtype of CRS known as allergic fungal rhinosinusitis has been relatively well described. Fungi are thought to serve both as immunogenic antigens and as adjuncts to inflammation through protease activity. Development of a recent murine mouse model of asthma bypassing the pre-sensitization of allergen further suggests a broader role for fungi in allergic asthma. The literature is lacking in defining a clear presence of fungi within the inflamed sinus cavity of CRS patients and its potential immunologic effects, as well as the utility of antifungal therapy for CRS management. We will review these data and potential common molecular mechanisms activated by fungi in the common pathway toward upper and lower airway inflammatory pathology.