Hemophagocytic lymphohistiocytosis (HLH) syndrome is an uncontrolled activation of macrophages, causing multiorgan dysfunction. The prognosis depends on the cause and the delay of diagnosis and treatment. Several infections can cause HLH, including rickettsia, a gram-negative bacterium. The diagnosis of rickettsia is based on clinical signs, including fever, headache, rash and sometimes tick bite site. The importance of an early diagnosis of rickettsia is the key. We present a case of rickettsia infection complicated with severe HLH occurring in a 21-year-old woman. The diagnosis was confirmed by serology 4 weeks after admission. She was treated with immunoglobulin, corticosteroids, and doxycycline with a favorable outcome.