Aspirin and food additives are known to induce bronchoconstriction, angioedema or urticaria in susceptible patients. To evaluate the incidence of hypersensitivity to aspirin and food additives, 36 subjects with bronchial asthma, 33 of whom were non-allergic asthmatics and 3 were allergic asthmatics who had a history of aspirin sensitivity, were challenged orally with six compounds: acetylsalicylic acid (ASA), sodium bisulfite, tartrazine, sodium benzoate, 4-hydroxy benzoic acid, and monosodium L-glutamate. Significant bronchoconstrictions were found in 15 (41.7% ) of the 36 subjects tested. Eight of the 15 subjects showed positive asthmatic responses to the aspirin, two showed asthmatic responses to the food additives, and five responded to both aspirin and the food additives. It is suggested that ASA and food additives could be causes of clinically significant bronchoconstriction in moderately severe non-allergic asthmatic patients.