A retrospective clinical study was done of 38 infants with temporary monosaccharide intolerance who were admitted to hospital between November 1976 and August 1978. There were two clinical groups. Group 1 consisted of 31 infants who developed monosaccharide intolerance as a sequela to acute gastroenteritis (i.e., 4% of infants admitted with acute gastroenteritis). Rotavirus was the cause of gastroenteritis in 64% of cases of monosaccharide intolerance. Monosaccharide intolerance was easily managed by dietary manipulations and lasted a mean of 2.5 days. Group 2 consisted of seven infants who developed monosaccharide intolerance during the course of protracted diarrhoea. The monosaccharide in-tolerance lasted up to 70 days, with a mean of 21 days, and required a period of total bowel rest followed often by complicated dietary manipulation.