The protocol is proposed in a definite way for recurrent or chronic symptoms. In the first case, the diagnosis is made by PRICK, RAST and provocation tests with suspect foods. On 100 patients, the reliability of PRICK and RAST has been shown. In the second case, a non-allergenic diet and the recurrence of symptoms on the re-introduction of certain foods has permitted isolation of the causative foods and the differentiation of food allergy and intolerance. This has been done with 386 cases of urticaria and angio-oedema, where it has been shown that 1.9% of the reactions had a food-linked origin.