BACKGROUND: Gastroenteritis remains a common and expensive illness. Oral rehydration solutions (ORS) have been shown to be effective in the prevention and treatment of dehydration, the prime cause for diarrhea-related morbidity and mortality. OBJECTIVE: To evaluate the ambulatory management of acute gastroenteritis in infants, and particularly practices concerning oral fluid therapy. METHODS: This prospective, multicenter study included 326 infants (mean age: 10 +/- 6 months), examined in a hospital for acute gastroenteritis, with or without dehydration. RESULTS: Before admission, 81% had previously been examined by a practitioner, and 89% of these practitioners had written a prescription. This prescription included ORS in 35% and was not different according to the age of the infant. Pediatricians prescribed ORS more frequently than general practitioners (respectively 58% vs 29%; P < 0.001). The failure rate of ORS prescription was 25% (two parents did not observe, ten children refused to drink, and eight stopped treatment because of vomiting). Lactose-free milks were prescribed in 46% of infants and the observance was 82%. At least one drug was prescribed in 94% of infants, with a mean of 2.6 drugs per infant; one antibiotic was prescribed in 33% of infants. Infants were admitted to hospital without any previous consultation in 18%, on the parents’ initiative but after at least one previous medical examination in 52%, and on the physician’s initiative in 30%. Thirty-three percent were dehydrated; one infant died and two had sequellae. CONCLUSION: The use of ORS remains insufficient. Efforts to improve use of ORS should be expanded beyond physician education.