In order to compare the antiplaque and antigingivitis activity of three commercially-available triclosan containing dentifrices with that of a placebo dentifrice without triclosan, a double-blind clinical study was conducted on 194 subjects over six months. Following baseline supragingival plaque and gingivitis examinations and a complete oral prophylaxis, subjects were stratified by their whole mouth baseline plaque (modified Quigley-Hein) and gingivitis (modified Löe-Silness) scores and then randomly assigned to one of four dentifrice using groups. Plaque and gingivitis examinations were then performed after six weeks, three months and six months use of the dentifrices. Subjects brushed twice daily in their customary manner. The triclosan/soluble pyrophosphate and the triclosan/zinc citrate commercially available dentifrices did not provide statistically significant reductions in either supragingival plaque accumulation or gingivitis at any of the examination intervals, as compared to the placebo dentifrice. The subjects using the commercially available triclosan/copolymer dentifrice had, after six months, statistically significant reductions in supragingival plaque (11.3 per cent), plaque severity (18.8 per cent), gingivitis (19.9 per cent) and gingivitis severity (27.8 per cent), as compared to the placebo dentifrice.