['High mobility group box 1 (HMGB1) protein is a chromatin protein that functions as a proinflammatory cytokine when secreted in response to inflammatory stimuli. The purpose of this study was to determine the relationship between the HMGB1 level in nasal secretions and the severity of inflammation in chronic rhinosinusitis.', 'This was a cross-sectional study.', 'Nasal secretions were obtained by irrigation of the affected sinonasal cavities with normal saline. Total 63 nasal lavage fluid samples were collected from 38 patients with chronic rhinosinusitis who underwent endoscopic sinus surgery. Levels of HMGB1 and tumor necrosis factor alpha, interleukin (IL)-1β, and IL-8 were determined by enzyme-linked immunoassay. Severity of inflammation was assessed by the Lund-Mackay scoring system, which is based on preoperative computed tomography scans. Concurrent medical disorders, presence of nasal polyps, septal deviation, and allergic rhinitis were also investigated.', 'The level of HMGB1 in nasal lavage fluid was positively correlated with the Lund-Mackay score. The score was the only factor associated with HMGB1 by univariate and multivariate analysis. Other cytokines, with the exception of IL-8, were not correlated with the Lund-Mackay score.'] Does level of secreted HMGB1 correlate with severity of inflammation in chronic rhinosinusitis?