In 3 cases of acrodermatitis enteropathica duodenal biopsy performed at the outset of treatment showed a similar abnormality of the intestinal mucosa. Further biopsies taken during treatment showed progressive improvement of the intestinal mucosa with subsequent complete restoration of the normal cellular and villous pattern. The initial treatment was with expressed human breast milk and oral di-iodohydroxyquinoline. The latter was continued alone and later replaced by zinc sulphate. Changes in the intestinal epithelial cells and inflammatory cell infiltration of the lamina propria still detectable on di-iodohydroxyquinoline therapy reverted to normal with oral zinc.