AIM: The aim of this pilot study was to evaluate the effectiveness of a mouthwash containing Triclosan and Gantrez in the reduction of bacterial biofilm and gingivitis. METHODS AND MATERIALS: Thirty patients were assigned to control and experimental groups. The visible plaque index and the marginal bleeding index were determined at the baseline, and at the second and third months, at which time a percentage of bacterial plaque and bleeding was obtained for each patient. All patients were given unlabeled toothpaste without Triclosan and Gantrez and soft-bristle toothbrushes. Additionally, the experimental group patients used unlabeled mouthwash with Triclosan and Gantrez. The participants were instructed to rinse for 60 seconds after brushing, twice a day. RESULTS: At the baseline, the control and experimental group's bacterial plaque and marginal bleeding indices were close to each other (46.61% and 50.75% respectively; 7.62% and 9.59% respectively). At the third month, the experimental group presented bacterial plaque and marginal bleeding indices of 6.56% and 0.43% respectively, while the control presented 11.37% and 2.41% respectively. There were no significant differences between the two groups (p>0.05), with a discrete tendency to better results in the experimental group for both variables. However, there were significant differences among the experimental periods (p<0.05), except between the second and third months of observation. CONCLUSION: The mouthwash did not bring forth an additional advantage when combined with brushing. Additional studies where the observation period may be prolonged and the number of subjects increased are recommended. CLINICAL SIGNIFICANCE: It is important to understand the role chemical control of supragingival plaque can play as an aid in the treatment of periodontal diseases. Since bacterial biofilm is the primary etiological factor in gingivitis and periodontitis, it is essential to know how to control it in order to provide a more complete therapeutic strategy for patient care.