during 2001,28,584 dhf patients from 19 provinces were reported to the pasteur lnstitute,ho chi minh city, viet nam,an increase of 52.53% in the number of cases as compared with 2000. seventy-one patients died in 2001,an increase of 44.89% in the case fatality rate as compared with 2000. tien giang and dong thap were the two provinces with the highest morbidity rate per 100000 population in the region and these rates were higher than the average morbidity rate for the five-year period 1996-2000. virological and serological surveillane were a part of the national programme for dhf control; these surveilance activities were carried out from the beginning of the year the present paper includes data collected during 2001.