A two-months-old male infant with gastroenteritis had been given a sports drink (Aquarius) by the general practitioner as a treatment for dehydration and was referred because of ongoing vomiting and weight loss. The child recovered after reinstitution of normal bottle-feeding and administration of a regular oral rehydration solution (ORS). The sports drink was analysed and found to contain less salt than ORS. As a result, the salt:sugar ratio was not optimal. Sports drinks are therefore contraindicated in the treatment of dehydration in children.