The aim of this study was to investigate the ability of Triclosan dentifrices to delay the development of gingivitis during a 21-day period without toothbrushing. Test pastes contained 0.3 per cent Triclosan; seven also contained 0.75 per cent zinc citrate; one other contained 2 per cent Gantrez. Plaque and gingivitis increased significantly (p < 0.001) between day 0 and day 21 in the control group. there was no evidence to reject the assumption of similar efficacy across the seven Triclosan/zinc citrate variants. For the combined Triclosan/zinc citrate groups, statistically significant reductions in plaque formation and in gingivitis relative to the control were recorded. Reductions in plaque and gingival bleeding compared to control for the Triclosan/Gantrez group were not statistically significant, although reductions in gingival indices were. The greater reduction in the Gingival Index of the Triclosan/zinc citrate group was also statistically significantly different from that of the Triclosan/Gantrez group, suggesting that a dentifrice containing the former would have a greater antigingivitis potential than a dentifrice containing the latter.