The authors describe a case of association cystic fibrosis coeliac disease, which they have observed. The frequency of this association in the general population is of 1:2,000,000. M.A. presents little growth in terms of height and weight and intestinal alterations (an abundance of fatty and mucous stool). The initial diagnosis was that of coeliac disease. After two months of diet without gluten one observed an increase in weight, but o result for the intestinal disturbances. The positive result revealed from the sweat-test and the study of genomic mutation (delta F508) showed the diagnosis of cystic fibrosis associated with coeliac disease. The specific treatment of both syndromes resolved intestinal alterations and caused the diminution of the acute bronchitis frequent during the first and the second infancy.