In a retrospective study, 9% of the admissions to Ben Taub General Hospital for diarrhea were found to have acquired monosaccharide intolerance (AMI). The course of AMI was compared with that of acute diarrheal syndrome (ADS). The patients with AMI were younger at the time of admission, and, although the mean birthweight and percent of prematurity were approximately the same in the two groups, the AMI patients were found to be malnourished (p less than 0.02). Data suggest that the nutritional insult had occurred between birth and admission, and that malnutrition was a contributing factor in the development of AMI.