A 35-year-old man with a history of intravenous drug use developed endocarditis due to Rothia dentocariosa that was complicated by a perivalvular abscess. Despite combined medical and surgical treatment, abscess formation progressed following aortic valve replacement, and the patient died during a second operative procedure. This is the sixth case of Rothia dentocariosa endocarditis reported in the English-language literature, and to our knowledge, the only case in which a perivalvular abscess has been documented.