Patients with chronic rhinosinusitis (CRS) have abnormal immune responses triggered by a variety of infectious agents, airborne toxins and fungi. Respiratory epithelial cells serve as relay stations capable of amplifying or augmenting cues received from external stimuli to nearby immune cells located in the sinus mucosa. Previous studies have identified increases in complement components and complement gene expression in the mucosa of patients with atopic CRS with nasal polyps (CRSwNP). As part of a larger study, we used shotgun proteomics to quantify changes in mucus proteins between patients with and without nasal polyps.