BACKGROUND AND METHODS: The author conducted a systematic review of the literature to evaluate the efficacy of antigingivitis and antiplaque products in six-month trials. He searched electronic databases for six-month randomized clinical studies that evaluated both antiplaque and antigingivitis properties of dentifrices or mouthrinses. In addition, the author solicited unpublished studies from manufacturers. RESULTS: Seventeen studies support the antiplaque, antigingivitis effects of dentifrices containing 0.30 percent triclosan, 2.0 percent Gantrez copolymer. There was no evidence of efficacy for triclosan products containing either soluble pyrophosphate or zinc citrate. Dentifrices with stannous fluoride had statistically significant, but marginally clinically significant, evidence of an antiplaque effect; however, there was both a statistically and clinically significant antigingivitis effect. The largest body of studies (21 studies) supported the efficacy of mouthrinses with essential oils. A smaller body of studies (seven) supported a strong antiplaque, antigingivitis effect of mouthrinses with 0.12 percent chlorhexidine. Results for mouthrinses with cetylpyridinium chloride varied and depended on the product's formula. CONCLUSIONS: The studies in this systematic review provide strong evidence of the antiplaque, antigingivitis effects of multiple agents. These results support the use of these agents as part of a typical oral hygiene regimen.