The experience with prophylactic therapy for cyclic vomiting syndrome (CVS) at Princess Margaret Hospital for Children, Perth, Western Australia was retrospectively reviewed by questionnaire. Data was collected from 31 patients, aged 2.9-21.75 years who reported a mean of nine attacks per year. Eleven patients had utilized prophylactic therapy. Parental assessment of benefit was recorded. Propranolol was the most effective agent with reported benefit in four of six cases, other antimigraine agents were deemed effective in two of seven cases. Anticonvulsants and antidepressants were not considered use ful. Homeopathic and vitamin supplements were thought to be beneficial in three of six cases. Prophylaxis was less likely to be beneficial in the more severe cases of CVS, but was of benefit in those patients whose attacks were precipitated by infection or who had features consistent with migraine. Prophylactic therapy with propranolol or serotonin receptor antagonists should be considered in children with frequent or severe symptoms.