This article focuses on the tools that are available to assess nasal airflow, their utility in clinical practice, and comparison between them. Assessment of the nasal airway traditionally relied on history and physical examination only. Recently, tools have been developed that aid the physician in completing an assessment by measurement of parameters that are directly or indirectly related to airflow. Many physiologic and pathologic conditions can influence the amount of airflow or nasal airway resistance. These conditions can include normal changes, such as the nasal cycle, or pathology, such as septal deviations, turbinate hypertrophy, tumors, synechiae, nasal congestion or obstruction, allergies, nonallergic rhinitis, and sinonasal polyposis. Objective measures can be used to assist the clinician to diagnose and treat nasal complaints and also for objective quantification for research.