A 16 year old female patient with systemic lupus erythematosus presented to rheumatology clinic with a new I-II/VI honking-quality mitral regurgitation murmur. The patient was initially evaluated by transthoracic echocardiogram that revealed mitral valve regurgitation and a large band of tissue under the mitral valve leaflets. Blood cultures were obtained and were negative. Transesophageal echocardiogram provided better visualization of the lesion and showed the band of tissue involving most of the chordae of the posterior mitral leaflet. A diagnosis of Libman-Sacks endocarditis was made given the aseptic nature of the lesions and the patient's underlying lupus. Aggressive management of the lupus showed reduction of the mitral regurgitation and the size of the lesion. Libman-Sacks endocarditis is best evaluated by transesophageal echocardiogram.