Gemella morbillorum was isolated from the blood of a 38-year-old woman with a 4-week history of fever. An echocardiogram showed a left atrial tumor. The patient was successfully treated by antibiotic therapy and early surgical excision of the tumor. Histological examination of the excised tumor revealed a typical myxoma with infiltrates of neutrophils and remnants of bacteria. To the best of our knowledge, this is the first reported case of infected left atrial myxoma caused by G. morbillorum.