Drug-induced sleep endoscopy (DISE) is a new tool in the work-up of patients with sleep-disordered breathing (SDB). We assessed the impact of DISE on the treatment plan of snoring patients. This is a single institution prospective longitudinal clinical trial. The setting is a private teaching hospital. A consecutive series of 100 snoring patients prospectively underwent a standardised questionnaire, clinical examination, rhinomanometry, allergy skin prick testing, DISE and polysomnography. Management plan before and after DISE evaluation was compared. In 61 patients (excluding 16 patients sent for continuous positive airway pressure, three patients refused sleep endoscopy and 20 were lost to follow-up), we compared the treatment plans. DISE showed single level airway collapse in 13 and multilevel collapse in 48 patients. The site of flutter did not add additional information as compared to the pattern and the location of the collapse. After DISE, the initial management plan changed in 41% of patients irrespective of the type of initial management plan. The only somewhat accurate initial treatment plan was uvulopalatopharyngoplasty (unchanged in 11/13 patients). Excluding moderate to severe obstructive sleep apnea patients DISE is an indispensable tool in treatment decision in all SDB patients. We suggest to simplify the protocol for DISE reporting.