Bacteria belonging to the genus Listeria have been isolated from food products of animal, plant, and fish origin, and are associated with infections in immunocompromised hosts, pregnant women, and infants. The species Listeria grayi has rarely been reported as a human pathogen. It has a unique antibiotic sensitivity profile. We describe a case of L. grayi bacteremia in a heart transplant recipient. The organism demonstrated a reduced sensitivity to ampicillin. The patient was successfully treated with a combination of vancomycin and ciprofloxacin.