Introduction Neisseria elongata (NE), a Gram-negative, rod-shaped organism, was previously thought to be non-pathogenic. However, in recent years it has become increasingly recognized as a rare cause of infective endocarditis. In this paper, we report a case of NE infective endocarditis and provide a review of the literature. Objectives To describe a case of NE endocarditis, and to review the literature in search of any similar cases of this rare condition. Case report Our patient is a 77-year-old, otherwise healthy female patient who was found to have mitral valve endocarditis with valve regurgitation. Discussion NE endocarditis is a rare condition that typically affects the left cardiac chambers and is associated with high risk of embolization. A literature review retrieved 35 other cases. Conclusions Our report underlines the rarity of NE endocarditis, insofar as relatively few cases have been reported. The bacterium presents similarities with HACEK organisms and can potentially cause infective endocarditis.