A patient was admitted to our hospital with fever of unknown origin, lymphadenopathy and moderate anemia. The diagnosis of scrub typhus (tsutsugamushi disease) was established on specific serologic demonstration of antibodies to the cross-reacting proteins OX-K antigen and reaffirmed by successful treatment with doxycycline. The diagnosis of hemophagocytic syndrome (HPS) was made on the cytologic findings of many histiocytes containing phagocytosed blood cells in the marrow aspirate. The hemophagocytosis phenomenon disappeared after the scrub typhus was successfully treated, thus suggesting the relationship between scrub typhus and hemophagocytosis. In a patient with rickettsial diseases including scrub typhus, associated with HPS, it is important to understand the relationship between the two disorders since the prognosis for HPS, if untreated, is very poor.