A 40-year-old woman with systemic lupus erythematosus (SLE) presented with high-grade fever and severe thrombocytopenia. Acalculous cholecystitis and thrombocytopenia were initially suspected to be complicated with SLE and vasculitis. Contrary to our expectation, however, the patient was finally diagnosed with Helicobacter cinaedi bacteremia. SLE patients show various symptoms, especially when their condition is complicated with vasculitis, which mimics H. cinaedi bacteremia. It is therefore difficult to provide a definite diagnosis. Physicians should be mindful of the presence of H. cinaedi infection.