Aspirin-sensitive asthma and aspirin-sensitive rhinosinusitis can only be identified by provocation with analgesics because there are no appropriate in-vitro-methods. In the USA the oral challenge is the preferred provocation method. However, due to possible side effects we use the bronchial provocation with lysine-aspirin in the Hochgebirgsklinik Davos-Wolfgang since 1979. In a pilot study in 1989 and a following controlled study we developed and then investigated the sensitivity, specificity and side effects of a nasal provocation test using lysine-aspirin. All aspirin-sensitive asthmatics had a decrease in nasal flow >40% following nasal lysine-aspirin, with no reaction to lysine control of appropriate pH and osmolality. Control groups of normals, hayfever, perennial rhinitis and non-ASA-sensitive asthma did not react to lysine-aspirin nasal challenge. No bronchopulmonary nor other side effects were recorded. Nasal provocation may be employed to diagnose aspirin-sensitive asthma, and is especially useful in those cases where oral and bronchial provocation are contraindicated.