Three cases of serious infection caused by Aerococcus urinae are presented: a patient with endocarditis and two patients with soft-tissue infection (phlegmon and balanitis respectively). The literature on Aerococcus urinae infections is reviewed and the antibiotic therapy discussed. Aerococcus urinae is a pathogen isolated primarily from urine specimens of elderly patients with local or systemic predisposing conditions. Most infections are mild, but serious infections such as endocarditis and septicemia/urosepsis have been described. Penicillin or ampicillin in combination with an aminoglycoside and close monitoring of the patient's clinical status and laboratory results would seem to be the best strategy for management of cases of serious infection.