This study compared the efficacy of four mouthwash solutions in reducing plaque and gingivitis over 6 months in a population with good oral hygiene: 1) two low-dose 0.06% chlorhexidine preparations, 2) a commercially available 0.1% chlorhexidine solution, 3) an amine fluoride/stannous fluoride solution, and 4) a water control. All solutions reduced plaque levels, but the 0.1% and 0.06% chlorhexidine solutions were more effective at 3 months. The 0.1% chlorhexidine solution also produced greater reductions in gingivitis than the control. However, it also caused more discoloration than potential alternative solutions.