A 40-year old Indigenous woman with a history of mitral valve replacement was admitted to the Royal Darwin Hospital, Northern Territory, for an elective cone biopsy of the cervix. During the admission, she had recurrent fever and joint pain of the left knee. Blood was cultured, and she was treated with broad-spectrum antibiotics. Abiotrophia defectiva was identified from the culture, and a transoesophageal echocardiogram revealed endocarditis of the mitral valve prosthesis. A review of the English-language literature suggests that this is the first reported case of Abiotrophia endocarditis in Australia, and the third reported case of prosthetic-valve endocarditis caused by this species worldwide.