We describe the case of a 26-year-old man who developed severe aortic valve insufficiency due to a culturenegative endocarditis, leading to severe heart failure. The diagnosis of Bartonella quintana endocarditis was suspected from the clinical presentation and serological immunofluorescence assay, and was confirmed by polymerase chain reaction analysis of excised valve tissue after aortic valve replacement. The aim of this report is to illustrate B. quintana endocarditis as an important cause of culture-negative endocarditis that presents challenges in its clinical, diagnostic and therapeutic management.