OBJECTIVE The aim of this study was to explore the difference between sinus bacteriology in chronic rhinosinusitis patients with and without nasal polyposis. We also analyzed the possible differences in culture results from swabs taken from the middle meatus versus the ethmoid sinus. METHODS Retrospective chart review of adult chronic rhinosinusitis patient data from the year 2006 to 2020. Nasal swabs were taken under endoscopic guidance either intraoperatively from either the ethmoid sinus or middle meatus, or in the outpatient clinic from the middle meatus. The results were categorized based on the most common microorganisms affecting the nose and sinuses. RESULTS We found that, the presence of nasal polyps seemed to have no effect on sinus bacteriology as whole. There was also no significant difference between the bacteriology of chronic rhinosinusitis patients who did not need surgery and those who did. Finally, we found that middle meatal cultures, taken endoscopically, give similar bacteriology results to that of ethmoid sinus cultures (taken intraoperatively). CONCLUSIONS Middle meatal culture results accurately represent true sinus flora, and therefore can be used to aid in appropriate culture guided antibiotic therapy for patients visiting the outpatient clinic.