Gemella morbillorum is a facultatively anaerobic Gram-positive coccus which forms part of the normal flora of the oro-pharynx and the upper respiratory tract. It rarely causes human infection but has been described previously in cases of empyema and lung abscess, septic shock, endocarditis, meningitis, and osteomyelitis. We describe a case of septic arthritis due to G. morbillorum occurring in an otherwise healthy 42-year old man and review previous reports of infection in the literature.