Aerococcus urinae is a rarely reported pathogen that often causes mild urinary tract infection (UTI), although serious complications such as endocarditis and septicemia have also been described. The organism may easily be missed or misidentified when using commercial detection systems. A. urinae is resistant to sulfonamides and, therefore, a typical treatment for UTI may be inappropriate. To date, 14 cases of A. urinae infective endocarditis (IE) have been reported, most of which were elderly males with predisposing conditions to UTI. Of these patients, eight died and 50% of survivors had severe neurological problems. The case is reported of blood culture-negative IE in a 69-year-old male. The patient recovered fully after undergoing aortic valve replacement and receiving a nine-day course of intravenous ceftriaxone, followed by peroral cefuroxime for the next 11 weeks. The causative agent was identified from the excised valve by bacterial broad-range PCR and direct sequencing of the 16S rRNA gene.