Diarrhoea and vomiting are common symptoms in children. In the majority of cases all that is required is some basic advice on management and appropriate reassurance. However, a few children will be at greater risk of complications or will deteriorate and require hospitalisation. GPs need to be able to differentiate between these groups and recognise the symptoms and signs requiring more active intervention. Guidance from NICE on the diagnosis, assessment and management of diarrhoea and vomiting in children under five provides a synthesis of evidence to aid GPs in the process.It also challenges some of the popular lay and professional myths that have developed around the management of gastroenteritis. [With external links to the evidence base]