Biofilms have been implicated in several head and neck infectious processes such as the following: dental and periodontal disease, otitis media, tympanostomy tube otorrhea, and chronic tonsillitis. We believe that biofilms also are associated with chronic rhinosinusitis. No information is known regarding the presence of biofilms in chronic rhinosinusitis.With institutional review board approval, tissue was obtained from consenting chronic rhinosinusitis patients who were undergoing functional endoscopic sinus surgery. Specimens were taken bilaterally from the ethmoid and maxillary sinuses. Inclusion criteria consisted of a positive diagnosis with pathologic tissue confirmation of chronic inflammation. Diagnosis was based on patient history, physical exam, and coronal sinus CT findings. Once collected, the specimens were labeled and fixed in formalin. The specimens were subsequently dehydrated, with successive immersions in increasing concentrations of diluted ethanol. The specimens were allowed to air dry and then were affixed to aluminum stubs with colloidal carbon. The sample surface was coated with a gold and palladium layer. The specimens were examined under an electron microscope. Areas of interest were photographed.Specimens from 5 patients were examined. All revealed bacterial biofilms. Invariably, biofilms were seen in the ethmoid, as well as in other samples. Denudation of ciliated and goblet cells was noted in all specimens. Biofilms resembled that of Staphylococcus species. Unidentified biofilms were also seen.This is the first documentation of biofilms in association with chronic rhinosinusitis. Further investigation is warranted, especially with control research subjects.