Chronic sinusitis comprises numerous disorders characterized by inflammation, mucous gland hyperplasia, and remodeling. Chronic hyperplastic eosinophilic sinusitis (CHES) is characterized by unrestrained proliferation of eosinophils, Th2-like lymphocytes, fibroblasts, goblet cells, and mast cells. The pathology of CHES is similar to that of asthma, and it is frequently diagnosed in association with asthma. It has been reported that exacerbations of CHES occur temporally with worsening of asthma; however, in the absence of well-controlled studies, this linkage remains unproven. In this article, the potential mechanisms linking these two diseases are examined.