As various drugs might have an effect on the fetus during pregnancy, the use of drugs should be minimized in the pregnant woman. Since bacterial vaginosis (BV) can be associated with prematurity and postpartum complications, we searched for alternative therapy for its cure during pregnancy. Commercial yoghurt incorporates both factors necessary for maintaining the protective mechanism of the vagina, vaginal pH and lactobacillus. A total of 32 women with BV in the first trimester of pregnancy were treated with intravaginal application of yoghurt. The result was favorable indicating that the continuous correction of vaginal pH and lactobacillus flora is crucial for normal vaginal ecology. During pregnancy, a local treatment restoring the normal acidity and vaginal flora, without systemic effect, may be preferable to any other treatment.