Chronic urticaria is defined as a daily or almost daily spontaneous occurrence of wheals that cause itching and lasting for at least six weeks. If there is no indication of a possible eliciting agent and because approximately 70% of patients benefit from it, a low-pseudoallergen diet should be carried out for 5 weeks. Although the low-pseudoallergen diet is successful, no explanation of the underlying mechanisms exists. On DBPC oral provocation testing with known food additives, only a small amount of patients, who experienced remission after a low-pseudoallergen diet react with new wheals and/or angioedema. For this discrepancy, natural food ingredients and new food additives are included in the dietary diagnostic. The high amount of substances, which are administrated within oral provocation testing can not reflect a realistic diet situation. Often it is impossible to ingest corresponding amounts of foods to reach the same concentration such as the provocation amount. Recording change reactions between food ingredients and the individual metabolism of the patients, the "step by step" food provocation method reveals itself to be most effective. In addition, individual predilections, amounts and frequency of ingested foods, are taken into consideration.