Nasal hypersensitivity is defined by an exaggerated response to certain specific stimuli such as a work-related agent, non-specific stimuli (irritant effect), or to allergic or inflammation mediators. The study of nasal hypersensitivity always involves provocation tests with other practical assays. In the occupational context, the provocation test most routinely used are "challenge tests", carried out with suspected substances provided by the patient, and non-specific tests with mediators (histamine and carbachol). Three complementary techniques-rhinomanometry, intranasal expiratory flow, and nasal lavage with cell and mediator studies, aim at three objectives. These are principally diagnostic and physiopathological, but are also possibly therapeutic. The authors describe in detail the technique of passive anterior rhinomanometry, nasal challenge tests and cholinergic challenges leading to a better understanding of non-specific nasal hypersensitivity. Future prospects concern the establishment of dose-response reactivity curves, exploration of the intranasal expiratory flows and research into nasal lavages with the study of cells and mediators released.