It is appropriate that we begin the clinical part of this conference with a discussion of acquired monosaccharide intolerance. This disease is the most severe form of carbohydrate malabsorption and maldigestion that can afflict an infant. The following article describes the pathophysiology of the disease, as well as its treatment, much of which was based on studies done by the Section of Pediatric Gastroenterology and Nutrition at Baylor College of Medicine. Acquired monosaccharide intolerance has almost disappeared from the United States but remains a problem in the developing world where it is included as part of the diagnosis of environmental enteropathy. Present research on this disease seems to sometimes duplicate what is already known.