Infant mortality from acute diarrhoea has sharply declined in the last few decades throughout Europe. However, acute diarrhoea is still a very common occurrence in European children, who experience, in their first 3 years of life, approximately 1 episode/year. The commonest agent responsible for infectious diarrhoeas appears to be rotavirus, followed by campylobacter. Although water loss may be high, the mean sodium loss is close to 40 mmol/l of stool in rotaviral diarrhoea, and to 60 mmol/l in diarrhoeas due to invasive pathogens such as campylobacter and salmonella. Larger fluid losses but a somewhat lower sodium loss accompanies non-cholera secretory diarrhoeas, which appear to be commoner in infants than in older children. This evidence indicates that an ORS for European children should have a sodium concentration lower than 90 mmol/l which was primarily intended for use in developing countries. Clearly, the glucose concentration is crucial, as it is now evident that concentrations higher than the recommended 110 mmol/l may lead, particularly in rotaviral enteritis, to worsening of diarrhoea and development of hypernatraemia. Finally, it appears that in Europe the use of commercially available ORS is strikingly low, so that infants and children are often given a variety of "clear fluids", generally inadequate to ensure proper rehydration or maintenance of hydration. Thus an effort should be made not only to devise the "ideal" solution, but also to effectively implement its use.