Q fever is caused by Coxiella burnetii, a Gram-negative, intracellular bacterium. Sheep and goats are the main reservoirs of this zoonosis, which is transmitted either by aerosols, over long distances via the wind or through milk or dairy products. Acute Q fever may be asymptomatic, or present as a flu-like syndrome, atypical pneumonia or hepatitis. Chronic Q fever manifests in a wide variety of ways, including blood culture-negative endocarditis, chronic hepatitis, osteoarticular involvement (spondylitis, arthritis, osteitis) or uveitis. Autoimmune diseases can be sometimes induced by chronic Q fever. Diagnosis is confirmed by serology and/or PCR in blood or tissues. The preferred treatment is doxycycline, and hydroxychloroquine is often added to potentiate the therapeutic effect of doxycycline in chronic or disseminated infections.