Standardized nasal provocation testing (NPT) has been shown to be a safe and very useful tool in the diagnosis of allergic and nonallergic rhinitis. However, in the United States, its use has been mostly limited to scientific investigations, and it has not yet been widely accepted as a standard diagnostic procedure in clinical practice. NPT aims to identify and quantify the clinical relevance of inhalant allergens or occupational irritants. During NPT, nasal respiratory mucosa is exposed to an airborne substance suspected to cause symptoms in the respective individual. Clinical reactions are monitored in a controlled and standardized fashion. Nasal secretions, symptoms such as itching, sneezing and, most importantly, nasal obstruction are assessed as well as ocular, bronchial, cutaneous, and systemic reactions. To achieve objective data on changes in nasal airflow and patency after the challenge, anterior rhinomanometry and acoustic rhinometry have been included in the standard protocol of NPT. By monitoring changes of nasal airflow on one hand and of nasal geometry on the other hand, these methods display nasal function in a graphic way just as speech and pure tone audiometry do for auditory function. Also, by their objective nature, these methods offer a clear and internationally comparable standard. This review outlines a protocol for NPT and discusses practical applications and clinical indications. The use of rhinomanometry and acoustic rhinometry as objective diagnostic tools is emphasized. For the diagnosis of allergic and occupational rhinitis, standardized NPT should be regarded as an international diagnostic standard.