Biclonal gammopathy is characterized by the presence of two different monoclonal immunoglobulins, and the clinical findings of biclonal gammopathy are similar to those of monoclonal gammopathy. An association between biclonal gammopathy and tsutsugamushi meningitis has not been reported previously. Here, we report a case of a 55-year-old man presented with fever and decreased mentality. A cerebrospinal fluid (CSF) test and an indirect immunofluorescent antibody test for Orientia tsutsugamushi revealed tsutsugamushi meningitis. CSF and serum immunofixation electrophoresis revealed biclonal gammopathy (IgG-
