Bacterial vaginosis frequently persists even after treatment.The role of several fastidious bacteria associated with bacterial vaginosis treatment failure remains poorly defined.The aim of our study was to define risks for bacterial vaginosis treatment failure,including pre-treatment detection of specific vaginal bacteria.Bacterial vaginosis is present when Nugent score≥7 and modified Amsel criteria are positive,women with bacterial vaginosis were treated with intravaginal metronidazole gel nightly for five nights.454 pyrosequencing method was applied to detect the bacteria of vaginal fluid.In the univariate analysis,history of bacterial vaginosis,IUD use,Facklamia,Corynebacterium and Veillonella were significantly associated with bacterial vaginosis treatment failure.Lactobacillus crispatus,L.pentosus and Megasphaera were significantly associated with cure.After a logistic regression analysis and detection of these bacteria at test-of-cure,we found women who had a history of bacterial vaginosis had higher incidence of BV treatment failure,noly women with L.crispatus had lower incidence.Post-treatment sexual activity was not associated with treatment effect.Our data suggested that the treatment failure may be not caused by drug-resistance,it have a closer relationship of a failed restore of lactobacillus.