Coxiella burnetii is an obligate intracellular bacterium that causes the zoonotic infectious disease, Q fever. The common clinical presentation is fever, hepatitis, and pneumonia; laboratory examination could reveal pancytopenia, elevated liver enzymes. In bone marrow, many fibrin ring granulomas, also known as "Doughnut" granulomas can be seen and suggest the diagnosis of Q fever. However, these bone marrow granulomas can also be presented in infectious diseases by other pathogens such as EBV, CMV, and HBV; therefore, other serology or PCR-based tests are needed to confirm the diagnosis of Q fever. We report the first case of acute Q fever in Vietnam, presented as a fever of unknown origin with hepatitis in a 53-year-old male patient. A bone marrow biopsy was performed and showed various fibrin ring granulomas; therefore, Coxiella was suspected and the diagnosis was confirmed by PCR. Some infectious diseases can cause specific changes in the bone marrow, such as Doughnut granulomas in Q fever. These features can help direct the diagnosis and decide earlier treatment for the patient.