An outbreak of febrile disease involving 170 Khmer adults at an evacuation site in Thailand occurred during the dry season of 1986, only 8 months after the camp was constructed. The illnesses were characterized by persistent fever, retro-orbital headache, myalgias, and clinical response to tetracycline within 2–3 days. The symptoms, effectiveness of tetracycline, and presence of a large rat population raised the suspicion of murine typhus. Fourteen (74%) of 19 patients had elevated or rising antibody titers against Rickettsia typhi, confirming the clinical diagnosis. Rats were caught, and they and their fleas were identified. In agreement with the known Thai host and vector, 80 (93%) of 86 rats were Rattus exulans, and all of 32 fleas were Xenopsylla cheopis. This first reported outbreak of murine typhus in Thailand is notable for its occurrence in a new human settlement only 8 months after construction.