The effect on the oral ecology of daily use, for seven months, of a dentifrice containing 0.5% (w/w) zinc citrate and a non-ionic agent, i.e., 0.2% (wlw) Triclosan (2,4,4’ -trichloro-2’ -hydroxydiphenyl ether), has been monitored on 13 adult volunteers. Plaque and saliva were sampled monthly and the bacterial flora analyzed. Twenty-six volunteers used a placebo dentifrice as part of their normal oral hygiene for four months to establish the baseline microbial flora. The volunteers were then split into two equal groups: One group continued to use the placebo dentifrice; the other used the dentifrice containing zinc citrate and Triclosan. There was no evidence that seven months’ use of a dentifrice containing 0.5% zinc citrate and 0.2% Triclosan caused shifts in the oral microbial ecology, nor was there any evidence of developing bacterial resistance to Triclosan.