in 2001,18 provincial centres for preventive medicine sent samples taken from DHF patients to the Arbovirus laboratory at the pasteur institute, Ho chi minh city. the provincer with the highest rates of virus isolation were tien giang and kien giang. dengue virus were mostly isolated from patients diagnosed with viral syndrome and DHF grades. dengue-2 virus caused many cases of severe disease (grade),as compared with other serotypes A total of 4,046 patient sera were by mac-elisa,the average positive rate was in areas with positive mac-elisa results,however,no control measures had yet been implemented to limid the increasing number of DHF oubreaks in the area.