OBJECTIVE: To assess the economic burden of gastroenteritis and, in particular, rotavirus-associated disease among children aged five years old and under, from the perspective of the health service, parents and society. METHOD: Over a period of three rotavirus seasons, stool samples were collected from 223 children who presented at GP surgeries with diarrhoea and vomiting. Parents were asked to complete a questionnaire detailing severity of illness, health care resource use, personal medical expenses, changes in child care patterns and associated costs, and lost income due to their child's illness. Data were analysed as a whole to establish the cost of illness of gastroenteritis and separately in terms of rotavirus and other viral strains. RESULTS: A total of 48% of the sample had rotavirus acute gastroenteritis; a further 21% had other virus-associated gastrointestinal disease. The average total cost of a child presenting with gastroenteritis and rotavirus-gastroenteritis ranged between £60-£176 and £59-£169 per episode, respectively, depending on the perspective. The annual cost of ‘normal' childhood illness was estimated to be between £205 and £323. Given the prevalence and severity of the disease, the estimate additional burden of gastroenteritis to society is £75.2 million per year, and for rotavirus gastroenteritis it is £57.2 million per year. CONCLUSIONS: Due to the nature and prevalence of rotavirus the total burden of illness is considerable. As well as being a major inconvenience to parents and children, it would appear that there is a considerable amount of cost shifting between the health service, parents and society. Some of the economic cost of the illness may be constrained with an immunisation programme; work is currently being undertaken to model the cost effectiveness of vaccination within the UK context.