Chronic Q fever is most commonly associated with culture-negative endocarditis and less frequently with infection of vascular grafts, infection of aneurysms, hepatitis, pulmonary disease, osteomyelitis, and neurological abnormalities. We report a case of chronic sternal wound infection, polyclonal gammopathy, and mixed cryoglobulinemia in which Q fever endocarditis was subsequently diagnosed. Polymerase chain reaction analysis of the wound tissue was positive for Coxiella burnetii DNA, and treatment of the endocarditis resulted in prompt healing of the wound. Chronic Q fever can occur without epidemiological risk factors for C. burnetii exposure and can produce multisystem inflammatory dysfunction, aberrations of the immune system, and persistent wound infections.