Bordetella holmesii is a recently recognized Gram-negative bacterium causing both pertussis-like respiratory symptoms and invasive infections, such as bacteremia, pneumonia, meningitis, arthritis, pericarditis and endocarditis. Few data are available on its epidemiological characteristics, mostly related to respiratory infections. However, these are frequently misdiagnosed as a Bordetella pertussis infection as most diagnostic tests routinely used are not species-specific, thus biasing the epidemiological studies of both strains, as well as the efficacy studies on pertussis vaccination. There is no accepted agreement on treatment and it remains unknown if antimicrobial prophylaxis is indicated in certain clinical settings. We review here the current knowledge on B. holmesii and the need for further research.