OBJECTIVES:  Dengue is the most rapidly-spreading mosquito-borne viral disease in the world. The disease is now endemic in more than 100 countries in the World Health Organization (WHO) regions. In 2014, Vietnam had recorded 43,000 cases in 53 provinces with 28 deaths. METHODS:  A cross-sectional study was conducted in six months between September 2015 and March 2016 at Cu Chi Provincial General Hospital. Cost-of-illness (COI) in this study is estimated under the incidence–based approach from the societal perspective. RESULTS: Among 168 patients were interviewed, proportion of adults suffering dengue fever are almost double that of children (64.3% vs 35.7%). The day loss of patient and caregiver were 7.8 ± 2.9 days and 7.6 ± 2.1 days, respectively. Study also found out the average cost per case was 139.3 ± 61.7 USD. The average cost per child was not significantly higher than per adult (151.0 ± 63.5 USD and 132.7 ± 59.9 USD, respectively; p = 0.068). The component with the highest proportion of total cost was the cost of hospital bed (50.2%). According to the sensitivity analysis, if the cost of hospital bed and ultrasonic cost was reduced by 10%, the total treatment cost of dengue fever will fall by 5% and 1.6%, respectively. CONCLUSIONS:  This study can be the basis for formulating investment plans and allocating funds for the treatment and prevention of this disease. In order to estimate the entire socioeconomics burden of disease due to dengue virus, a larger study including both dengue fever and dengue hemorrhagic fever, in several hospitals is needed.