Wetreated a case of Tsutsugamushi disease diagnosed by polymerase chain reaction (PCR) using a scab specimen at the bite site of trombiculid mites. Otherwise the diagnosis could not be confirmed by serum antibody test nor the PCRtest of blood. The genome of Rickettsia tsutsugamushi was detected and identified as the Kawasaki serotype strain. Anattempt to extract the genomefrom the scab has not been reported, thus our data suggest that the scab is a useful specimen to confirm the diagnosis of Tsutsugamushi disease. (Internal Medicine 41: 408-411, 2002)