Clinical features, hypersensitivity mechanisms, and differential diagnosis of cereal allergy or intolerance were investigated in children with atopic dermatitis (AD). On oral provocation, 18 children exhibited a positive response to wheat, three to rye, one to barley, and one to oats. Cereal-induced symptoms were dermatologic, gastrointestinal, or oropharyngeal, and their onset after provocation was immediate (eight cases), delayed (14 cases), or both immediate and delayed (one case). A combination of type I allergy tests (prick test, RAST, and histamine-release test) detected all immediate reactors and 9/14 delayed reactors. Of the five subjects remaining negative in these tests, three were positive in the patch or lymphocyte-proliferation tests. Subjects with cereal allergy or intolerance frequently possessed IgE, IgA, and IgG antibodies against gliadin, but only one of these children was HLA-DR3-positive, and none had reticulin antibodies typical of celiac disease. Combining tests of immediate and delayed hypersensitivity can confirm allergy to cereals in a more reliable way. The coexistence of cereal allergy and celiac disease seems to be rare.