We report a case of a 39 year-old woman with transfusion-induced malaria presenting as fever of unknown origin. She had been well until 2 months ago when lower abdominal pain developed. Pelvic ultrasonography revealed an ovarian mass and an operation was performed. Two weeks after the operation, she developed a fever. Peripheral blood smear revealed developmental stages of Plasmodium vivax. The patient had received two units of whole blood during the operation, which was later proven to have been donated by a asymptomatic soldier who contracted tertian malaria while serving near the DMZ, an endemic area of malaria in South Korea. Considering such a case, malaria should be included in the differential diagnosis of post-transfusion febrile episodes.