Ninety patients suffering from recurrent urticaria were orally exposed to 500 mg acetyl salicylic acid (ASA). 36.6% proved to be ASA intolerant in this group. 26 ASA-positive and 18 ASA-negative probands were selected to take part in an additional provocation test with 8 different food additives (preservative and colouring matters). Altogether 31 tests sheets were exaluated. Urticarial reactions were seen after administration of p-hydroxybenzoic acid methylester (5), p-hydroxybenzoic acid propylester (6), benzoic acid (9), sodium benzoate (6), tartrazine (6). Ponceau rouge (5) and indigo carmine (3). Detailed research was carried out on the occurrence of the tested substances. With a diet avoiding salicylates, benzoates and colouring matter 20% of these patients recovered spontaneously and became symptom-free, whilst a further 55% of cases showed marked improvement.