The histochemical characteristics of the mucosubstances of the different parts of the human alimentary tract in some inflammatory conditions (chronic gastritis, gastric and duodenal ulcers, diverticulitis, Crohn’s disease and ulcerative colitis) have been investigated using modern histochemical techniques. There is a marked increase in the production of sialomucins in most inflammatory conditions but the mucosubstances secreted are similar to those normally present. Histochemical techniques for mucosubstances may be of value in differential diagnosis. © 1969, The British Empire Cancer Campaign for Research. All rights reserved.