Aim of the present study was to investigate whether the use of an oxidising mouthrinse as an adjunct to chlorhexidine is efficacious in reducing stain, plaque and gingivitis. This study had a single-blind, 2-group parallel design, including a 14-day experimental non-brushing period during which 1 group (n = 14) used chlorhexidine alone (CHX) and the other (n = 14) used chlorhexidine in combination with an oxidising agent. Patients were randomly assigned to either group. The gingival condition was evaluated at baseline by means of bleeding on marginal probing. The examination after 14 days of rinsing included the evaluation of plaque, bleeding on marginal probing and stain (GMSI: gingival modification of the stain index). The results showed at day 14 a significant difference between the 2 groups for plaque and gingival bleeding. The proportion of stained surfaces was less in the CHX + PER-group (28%), than in the chlorhexidine group. The adjunctive use of an oxidising agent peroxyborate to chlorhexidine, proved to be superior to chlorhexidine alone with regard to the inhibition of plaque and development of gingivitis.