Sleep nasendoscopy was conceived at the Royal National Throat, Nose and Ear Hospital, UK in 1991, and has remained fully implemented in patient selection for targeted treatment of the spectrum of sleep-disordered breathing. The senior authors (B.T.K. and P.B.) have been performing sleep nasendoscopy together for over 10 years, and we look back at their decade's experience. A retrospective audit study based on case notes was performed over a 10-year period (1995-2005) in a tertiary-referral practice setting. Case notes were retrieved on all patients who had undergone sleep nasendoscopy during the study period, and agreed data were extracted and analyzed. A total of 2,485 sleep nasendoscopies were performed in patients with a mean age of 44.1 years, a 4:1 male preponderance, and a mean body mass index of 27.3 kg m(-2). Sleep nasendoscopy grading correlated well with apnoea-hypopnoea index and mean oxygen desaturation. Such grading helped us define and discuss treatment options with patients. After a median follow-up period of 518 days, 72% of patients reported feeling better; 26% of patients reported no change; and only 2% of patients reported feeling worse after treatment. Sleep nasendoscopy has proved to be a useful adjunctive method to identify the anatomical site of snoring, not to mention upper airway collapse, and remains integral to our tertiary-referral practice. It has allowed us quality assessment of the dynamic anatomy of sleep-disordered breathing that most closely and cost-effectively simulates the natural situation of patients. And for targeted treatment, such assessment has been fundamental.