The epidemic of tsutsugamushi disease, along with hemorrhagic fever with renal syndrome(HFRS) and leptospirosis, has been ingrowing concern as it occupies a considerable proportion of the so-called seasonal febrile illnesses in autumn in Korea. This study was conducted to describe certain epidemiologic characteristics of the reported cases of the tsutsugamushi epidemic in Chollanamdo province in 1991. The findings could be summarized as follows: 1. Among three seasonal febrile illnesses in Autumn, tsutsugamushi disease occupied 91.9 percent of whole serologically confirmed cases. 2. Male-female sex ratio was 1 : 1.8. Majority of cases (77.4% in men, 65.1% in female) were in older age group (>=50 year of age). 3. Date of disease onset were distributed between late September and November. The 67.4% of cases were developed from October 21 to November 10, 1991. 4. The 41.5% of cases were reported from southern maritime districts. Reported dates of index cases and median cases were earliest in inland districts followed by southern maritime and latest in western maritime districts. 5. Most frequently reported clinical symptoms were chill (100%), high fever (100%), headache (81.7%), and skin eruption (70.4%).