Chronic rhinosinusitis (CRS) is a heterogeneous disorder with diverse responses to conventional anti-inflammatory medical and surgical treatments. Even for the newly developed mAbs targeting type 2 (T2) reaction, a considerable number of patients with CRS with nasal polyps (CRSwNP) exhibited unsatisfying response. Identifying patients with a tendency to poor prognosis is critical for selecting targeted therapies to improve the treatment outcome. This review focuses on clinical and biological markers associated with prognosis of CRS patients under conventional medical and surgical treatments and provides an update summary of potential markers for T2 biologics.Allergic rhinitis, asthma, prior sinus surgery, nasal polyps, tissue eosinophilia and neutrophilia, blood eosinophilia and high levels of Charcot-Leyden crystal, cystatin SN, chemokine (C-C motif) ligand 17, macrophage inflammatory protein-1β and interleukin (IL)-5 in nasal secretions have been associated with poor prognosis in CRS patients under conventional medical and surgical treatments. Blood eosinophil level might be a biomarker for anti-IL-5 (mepolizumab) and anti-IL-5R (benralizumab) biologic in patients with refractory CRSwNP.Several clinical and biological markers have been associated with poor response to conventional treatments in CRS patients; however, majority of them should be verified by large-scale multicentre studies. More efforts are needed to identify biomarkers for biologics.Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.