To understand the seroepidemiological patterns of murine typus in Korea, total of 2,625 patients with acute febrile episode from 1990 to 1992 were surveyed using indirect immunofluorescent antibody test (IFA). The strains of Richettsia typhi, Ehrlichia sennetsu, R. conori, R. sibirica, R. prowazekii, R. tsutsugamushi, R. akari, Coxiella burnetii, and R. japonica were used as the antigens and compared the cross-reactivity. The results are summarized as follows. 1. Seropositive rate of murine typhus among acute febrile disease was 2.3% as excluding highly cross-reacted sera to other Rickettsial antigens. 2. Sera reacted to R. typhi showed the cross reaction in the order of E. sennetsu, R. conori, R. sibirica, R. prowazekii, R. tsutsugamushi, R. akari, C. burnetii, and R. japonica respectively. 3. Among the seropositives of murine typhus, male outnumbered female. 4. The age of the fifties showed the higher proportion than other age groups. 5. Murine typhus seems to occur throughout the country in Korea. 6. Murine typhus was the most prevalent in November and December.