To report a case of HIV infection presenting with thrombotic thrombocytopenic purpura (TTP) and brucellosis that responded well to plasmapheresis and anti-infective therapy. A 64-year-old woman with moderate confusion, fever and pancytopenia was admitted. HIV infection history was taken from her family and she was not receiving antiretroviral therapy last one year. She had generalized purpuric skin lesions. Wright tube agglutination test was found positive with a 1:160 dilution and the patient was diagnosed as brucellosis. Detailed literature search showed brucellosis as a possible cause of TTP. Patient was treated by plasma exchange/fresh frozen plasma and antimicrobials and the response was excellent. Although brucellosis seems to explain the clinical picture of this patient, it is revealed that broad differential diagnosis is needed to reach uncommon diagnosis like TTP particularly in HIV infected patients.