Bacterial vaginosis (BV) is a common cause of vaginal discharge in women of childbearing age. In some individuals, it recurs frequently after treatment, frustrating both the patient and the physician. Standard BV treatment--metronidazole or clindamycin, administered either intravaginally or orally--is followed by relapse in approximately 30% of cases, within one month. Our inability to prevent relapse reflects our lack of understanding of how BV originates. BV has been associated with infectious morbidity in obstetrics and gynecology. Recent studies have found it to be a risk factor for HIV spread. These findings increase the need for us to be able to control recurrent BV and reduce its prevalence in the general population.