BACKGROUND : The impact of Staphylococcus aureus on onset of nasal polyposis has been the focus of numerous studies, but there have been few studies of other germs found in the ethmoid of operated patients or of their impact on post-operative results. METHODS : All patients undergoing endoscopic radical ethmoidectomy for nasal polyposis in the teaching hospital of Nantes (France) between 2006 and 2016 had intraoperative ethmoid cavity bacterial sampling. Phenotypic characteristics, pre- and post-operative symptoms and endoscopic findings were analyzed. Mann-Whitney tests and Kruskal-Wallis correlation analysis were used to assess clinical/bacteriological correlations. OBJECTIVE : The main objective was to describe bacterial colonization of patients undergoing surgery for nasal polyposis, and to assess correlations with phenotypic features, functional results and postoperative clinical course. RESULTS : One hundred and seven patients were included. A total of 26% were not infected, 55% mono-infected and 19% multi-infected. In 27.3%, staphylococci were isolated; in 30.5%, isolates were gram-negative bacilli. There were no significant correlations between presence or type of pathogen and symptom profile. CONCLUSIONS : This study confirmed the high rate of pathogenic bacteria in nasal cavities in case of polyposis, with high frequencies of S. aureus but also of gram-negative bacilli, raising the question of their involvement in the inflammatory reactions underlying the nasal polyposis.