Histamine release from the mucosa of the antrum, corpus and duodenum was induced in-vitro by wheat, egg, milk or fish. For this purpose 18 particles of mucosa were taken from each of 40 patients suffering from various diseases. Simultaneously, blood was drawn for the same procedure and skin tests were performed using the same solutions. A significant release of histamine was objectified in the majority of specimens. The greatest amounts were observed in mucosa of the corpus on incubation with wheat, and in patients with inflammatory diseases. There was, in contrast, no histamine release from blood. Skin tests were negative. Results point to a non-allergic phenomenon rather than an immediate-type hypersensitivity.