A case is reported of a seven-year-old girl who had concurrent infections with Plasmodium falciparum malaria and dengue in a remote area of East Timor. The diagnosis of malaria was delayed because of two false-negative results with malaria rapid diagnosis test cards. Diagnosis was eventually made on microscopic examination of the patient's blood. Despite treatment, the patient subsequently died. This case serves as a reminder of the fallibility of rapid diagnostic tests, and the importance of examining the patient's blood microscopically if malaria is suspected.