Introduction: Several studies have shown the importance of the objective evaluation of nasal patency for a better knowledge of nasal obstruction. Acoustic rhinometry (AR) is a recently developed objective technique for assessment of geometry of the nasal cavity. The technique is based on the analysis of sound waves reflected within the nasal cavities. Since its first description in 1989, AR has been applied in many studies of nasal geometry. Objective: This paper aims to review and to discuss the technique, the limitations and the clinical indications of acoustic rhinometry. Conclusion: The AR is useful to evaluate the nasal patency, and it is more effective when changes in nasal geometry are compared before and after a stimulus. In order to evaluate a nasal obstruction, it is very important to get objective values for an exact comprehension of this complex symptom.