Salifluor (5-n-octanoyl-3'-trifluoromethyl-salicylanilide), a broad spectrum antimicrobial agent, was investigated for its ability to inhibit dental plaque formation. A combination of salifluor with PVM/MA copolymer and NaF was optimized for its antiplaque effect in mouthrinse and dentifrice formulations based on a series of both laboratory and clinical studies. It was found that salifluor, a highly hydrophobic compound, could not be adequately solubilized with the conventional amount of sodium lauryl sulfate (SLS), the most commonly used anionic surfactant in oral hygiene products. However, it was possible to prepare stable mouthrinse formulations using a mixed surfactant system containing both anionic and nonionic surfactants. The most suitable mixture was found to be a combination of SLS, Pluronic and Tauranol in a proportion of 1:1:1. This combination provided adequate stability and high antimicrobial activity as determined by in vitro microbiological tests. Addition of a PVM/MA copolymer to the formulation improved the adsorption and retention of salifluor on stimulated tooth surfaces in vitro (saliva coated hydroxyapatite disks) by almost two-fold and also increased the antiplaque efficacy in both laboratory and human clinical studies. It was also found that a non fluoride dentifrice containing a combination of salifluor and PVM/MA copolymer with a dicalcium phosphate dihydrate abrasive, was highly effective in reducing smooth surface and fissure caries in rats. The results of the present studies demonstrated that salifluor is an effective antiplaque agent in mouthrinse and dentifrice when carefully formulated to maximize its delivery and bioavailability on oral surfaces. They also illustrated the difficulties encountered in exploiting the antimicrobial efficacy of highly hydrophobic, nonionic antimicrobial agents such as salifluor in commonly used oral hygiene vehicles.