OBJECTIVE: To assess the cost-effectiveness of outpatient sinonasal surgery in terms of clinical efficacy and control of expenses. METHODS: A retrospective study was conducted from January 2014 to January 2016. Patients scheduled for outpatient sinonasal surgery were systematically included. Clinical data were extracted from surgical and anesthesiology computer files. The cost accounting methods applied in our institution were used to evaluate logistic and technical costs. The standardized hospital fees rating system based on hospital stay and severity in diagnosis-related groups (Groupes homogènes de séjours: GHS) was used to estimate institutional revenue. RESULTS: Over 2years, 927 outpatient surgical procedures were performed. The crossover rate to conventional hospital admission was 2.9%. In a day-1 telephone interview, 85% of patients were very satisfied with the procedure. All outpatient cases showed significantly lower costs than estimated for conventional management with overnight admission, while hospital revenue did not differ between the two. CONCLUSIONS: This study confirmed the efficacy of outpatient surgery in this indication. Lower costs could allow savings for the health system by readjusting the rating for the procedure. More precise assessment of cost-effectiveness will require more fine-grained studies based on micro costing at hospital level and assessment of impact on conventional surgical activity and post-discharge community care.