Anthropometric measurements were performed on admission and at four weeks post discharge on 25 adults referred to hospital with acute gastroenteritis. There was a significant change in weight (P < 0.001) and mid-arm circumference (P < 0.05), but no change in skinfold thickness, arm muscle area or arm fat area. The results suggest that weight change during acute gastroenteritis is more a consequence of dehydration than of malnutrition.