Hypoxia-inducible factor-1 (HIF-1) is considered as a key molecule in regulating Th17:regulatory T-cells (Tregs) balance. The aims of this study were to investigate whether HIF-1 is associated with the ROR (RAR-related orphan receptor gamma) expression of Tregs in nasal polyps and to verify whether Staphylococcus enterotoxin B (SEB) is involved in this process.,Clinical experimental study.,Forty patients with chronic rhinosinusitis with nasal polyposis were enrolled and divided into eosinophilic nasal polyps (EPs) and noneosinophilic nasal polyps (NEPs) according to the proportion of eosinophils. Fifteen subjects who were undergoing septoplasty were enrolled as control subjects. Expression of HIF-1 in the tissue was measured using reverse transcriptase-polymerase chain reaction (RT-PCR), Western blot, and flow cytometry. The mRNA expression of RORC (RAR-related orphan receptor C) and HIF-1 in Tregs separated from tissues were measured by RT-PCR. Double immunofluorescent staining for RORC/FOXP3 and HIF-1/FOXP3 were conducted on the tissues. Expression of RORC and HIF-1 in Tregs from peripheral blood mononuclear cells (PBMCs) was measured using flow cytometry after stimulation with SEB.,Expression of RORC and HIF-1 in Tregs was significantly higher in EPs and NEPs compared with control mucosa, and there was a significant correlation between RORC and HIF-1 expression in Tregs. Expression of RORC and HIF-1 mRNA in Tregs separated from the tissues was also significantly higher in nasal polyps compared with control mucosa. Expression of RORC and HIF-1 in Tregs were increased after 24-hour stimulation with SEB in the PBMCs.,HIF-1-induced RORC expression in Tregs may play a key role in the pathogenesis of nasal polyps.