We describe a case of Q fever infection with an inflammated proximal ascending aortic aneurysm in an HIV-infected patient. The patient was treated with aortic root replacement and medication for Q fever, a combination of doxycycline and hydroxychloroquine in addition to highly active antiretroviral therapy. The combination of Q fever and HIV infection has rarely been documented. A case of Q fever infection of a proximal ascending aorta aneurysm in a patient with HIV co-infection has never been described before.