A field survey was carried out to determine the prevalence of active epilepsy in northern Vietnam between January and December 2005, when members of approximately 13,000 households were screened for seizure disorders. A clinical examination of all screened positive was performed by a neurologist to verify the epilepsy diagnosis, and all epilepsy cases were offered an EEG. Out of 47,269 screened, 1,338 (2.8%) had a positive response to the questionnaire. Of these, 206 fulfilled the criteria for active epilepsy, yielding a prevalence of 4.4 per 1,000 (95% CI 3.8-5.0), higher among males (5.1) than females (3.7), among those with lower compared with higher education and among single compared with those married. Only 20.6% were seizure-free the year before the examination. The prevalence of active epilepsy in Vietnam is similar to some other Asian countries but lower than in developing countries from Africa and South America.