103 adult subjects completed a supervised 2-week double-blind controlled clinical study to determine the effect of using either listerine antiseptic (LA) or its vehicle control (VC), as the only oral hygiene procedure, in inhibiting the development of and in reducing plaque and experimental gingivitis. Following baseline examinations, half-mouth prophylaxes were performed on each subject, who continued normal oral hygiene and returned 4 or 5 days later for a second baseline. Subjects then rinsed, under supervision, either 2 or 4 times daily for 2 weeks with LA or twice daily with VC, but suspended all other oral hygiene measures. Plaque and gingivitis were evaluated at baselines and after 2 weeks. Subjects using LA 2 or 4 times a day as the only oral hygiene procedure for 2 weeks demonstrated highly significant inhibition and reduction of both supragingival plaque and gingival inflammation compared to those using VC.