A 53-year-old man presented with nonspecific symptoms, evidence of aortic valve regurgitation and hepatosplenomegaly. Blood cultures grew Cardiobacterium hominis after 14 days of incubation. Endocarditis is caused by fastidious organisms such as C hominis in less than 5% of cases. To date approximately 40 cases of endocarditis due to this pleomorphic facultative anaerobic Gram-negative bacillus have been reported. C hominis is part of the normal human mouth flora.