BACKGROUND: Dengue, a mosquito-borne flavivirus infection, is endemic in Southeast Asia. Currently, the incidence has been increasing among adults. CASE PRESENTATION: A 26-year-old Thai woman, G1P0 31 weeks pregnancy, presented with epigastric pain for 1 day. She also had a high-grade fever for 4 days. The physical examination, complete blood counts as well as serology confirmed dengue fever. The patient was under conservative treatment despite severe thrombocytopenia. She was well at the 3rd day of discharge and 1-week follow-up. The pregnancy continued until term without any complication and she delivered vaginally a healthy female baby. CONCLUSIONS: More cases of dengue infection in pregnancy can be found due to the increasing incidence during adulthood. It should be suspected when a pregnant woman presents with symptoms and signs like in a non-pregnant. Conservative treatment should be conducted unless there are any complications.