A total of 294 adult male and female subjects completed a 6-month, double-blind clinical trial designed to evaluate the effects of a dentifrice which contained 0.3% triclosan in conjunction with 2% of a methoxyethylene/maleic acid copolymer in a 0.243% sodium fluoride/silica base, relative to a control dentifrice, on supragingival plaque accumulation and gingivitis. Plaque and gingivitis were scored after 3 and 6-month use of the assigned dentifrice. At the end of the study, the triclosan group showed an average reduction, relative to the control group, of 12% in plaque accumulation and 20% in gingivitis. Both were statistically significant at p < or = 0.0001. The effect of the triclosan dentifrice was most pronounced on the more severe manifestations of plaque and gingivitis. The improvement in the gingival parameters at 6-months relative to the control dentifrice was statistically significant at p < or = 0.0001. It was concluded that the twice-daily use of the triclosan-containing dentifrice resulted in significant reduction in supragingival plaque formation and a significant improvement in gingival health without the presence of any extrinsic staining or objectionable taste.