Introduction: Acoustic rhinometry (AR) is an objective method to study the geometry of the nasal cavity. Based on sound reflexion analysis, it provides an estimate of the cross section area of the nasal cavity as a function of the distance from the nostril. It is used to detect changes in nasal patency produced by decongestants, posture and nasal cycle. It is also used to objectively measure the success of nasal obstruction surgery. Objective: To evaluate the role of AR in measurement of nasal patency before and after septoplasty associated with turbinectomy or cauterization of the inferior turbinates. Methods: Thirty three patients with average age of 36 years were prospectively evaluated through AR before and 2 to 9 months after surgery. This protocol included an anterior rhinoscopy, estimation of global obstruction on a numeric scale by the patient and acoustic rhinometry of each side before and 5 minutes after nasal decongestion with adrenaline spray. Analysis of the data was performed with the t Student test. Results: Thirty one patients (93,9%) noted an improvement of subjective nasal patency after surgery. Minimal crosssection area and volume of the preoperatively narrower side increased with surgery as the nasal fossa resistance decreased. Conclusion: In our opinion, AR allows an objective measurement of nasal geometry pre and postoperatively and has legal and educational purposes.