Chronic rhinosinusitis (CRS) is a heterogeneous disease characterized by local inflammation of the upper airways which persists for at least 12 weeks. CRS is one of the most common chronic diseases in adults in the United States, affecting over 30 million Americans. CRS is frequently divided into 2 types: CRS with nasal polyps (CRSwNP) and CRS without nasal polyps (CRSsNP). Histologic studies have demonstrated significant tissue eosinophilia in CRSwNP. T cells in the mucosa are elevated in both forms of CRS and are skewed towards Th2 cytokine expression in CRSwNP. However pathogenic role of CRS has not been fully explored. To screen for pathogenic factors in CRS, we performed a microarray study. We collected uncinate tissues (UT) from 6 subjects with CRSsNP, 6 subjects with CRSwNP and 6 control subjects and nasal polyp (NP) tissues from 6 subjects with CRSwNP and then evaluated gene expression profiles using Affymetrix Human Genome U133 plus 2.0 array.