BACKGROUND AND OBJECTIVES: Vaginal acidification has been suggested as a means of normalizing the vaginal flora. GOAL: The purpose of this study was to determine the effectiveness of an acetic acid-based vaginal gel in the treatment of bacterial vaginosis (BV). STUDY DESIGN: Forty-four patients with BV were enrolled in a randomized, double-blind clinic trial. Of these, 29 were evaluable. Patients were randomized to receive either 5 mL acetic acid gel (n = 14) or placebo gel (n = 15) intravaginally twice daily for 7 days. Clinical criteria and vaginal Gram stain scores were compared between the initial visit and at 2 weeks after initiating therapy. RESULTS: No significant differences were noted when comparing drug and placebo in terms of subjective or clinical improvement or improvement in Gram stain smears for bacterial vaginosis. CONCLUSION: Vaginal acidification with an acetic acid gel formulated to pH 3.9 to 4.1 was ineffective therapy for bacterial vaginosis.