Recent immigrants and refugees constitute a substantial proportion of malaria cases in the United States, accounting for nearly one in 10 imported malaria cases involving persons with known resident status in 2006. This report describes three cases of Plasmodium falciparum malaria and two cases of Plasmodium ovale malaria that occurred during June 27-October 15, 2007 in King County, Washington. The infections were diagnosed in Burundian refugees who had recently arrived in the United States from two refugee camps in Tanzania. Since 2005, CDC has recommended presumptive malaria treatment with artemisinin-based combination therapy (ACT) (e.g., artemether-lumefantrine) for refugees from sub-Saharan Africa before their departure for the United States (2). Rising levels of resistance to the previous mainstays of treatment, chloroquine and sulfadoxine-pyrimethamine, prompted CDC to make this recommendation. Implementation has been delayed in some countries, including Tanzania, where predeparture administration of presumptive ACT for refugees started in July 2007. The cases in this report highlight the need for health-care providers who care for recently arrived Burundian and other refugee populations to be vigilant for malaria, even among refugees previously treated for the disease.