Background: Vaginal pH is a key factor in maintaining a healthy vaginal ecosystem. An increase in vaginal pH is commonly observed during bacterial vaginosis. Objective: This study was undertaken to compare the effects of polycarbophil, a new bioadhesive polymer in gel form, with those of an acidic vaginal douche on restoration of physiol. vaginal pH in women with a vaginal pH ≥4.5 and suspected bacterial vaginosis. We also assessed the pH-lowering effect of a single application of polycarbophil compared with that of a single application of acidic vaginal douche in an addnl. group of women. Methods: In this controlled, randomized, investigator-blinded study, women aged between 18 and 60 yr with a vaginal pH ≥4.5 and suspected bacterial vaginosis who were attending a gynecol. outpatient clinic for a routine visit were randomly allocated to receive polycarbophil gel 2.5 g or an acidic vaginal douche twice a week for 6 wk. We determined vaginal pH by means of a pH meter and the presence of a fishy vaginal odor using a potassium hydroxide (whiff) test at baseline and after each treatment. Vaginal pH was measured in the lateral vaginal fornix at baseline and at weeks 3 and 6 by an investigator who was blinded to treatment. In an addnl. group of women with a baseline vaginal pH >5.0, we assessed the effect of treatment after a single application of polycarbophil or douche on vaginal pH at baseline and at 8, 32, 56, and 80 h. Results: Of 45 women screened, 30 women, 2 of whom were pregnant, participated. All completed the study. An addnl. 8 postmenopausal women (mean age 56±5 yr) received a single application of polycarbophil (n = 4) or vaginal douche (n = 4). Polycarbophil significantly (P < 0.001) reduced vaginal pH from 5.4 to 4.7±0.6 at week 3 and 4.6±0.7 at week 6 compared with baseline and with the vaginal douche group (5.4±0.5 at week 3 and 5.3±0.8 at week 6; not statistically significant). At the end of the study, vaginal pH was significantly (P < 0.04) lower in the polycarbophil.