This study was designed to examine the efficacy of plant-derived active substances in a combined application of toothpaste and mouth rinse on dental plaque and sulcus bleeding index and the pH values of the saliva. 50 healthy students of dentistry without periodontal diseases took part in this study. Over a period of 4 weeks half of the group used herbs, while the other half used a placebo preparation. The data of the oral examination were always obtained at 12 a.m., with the last food intake at least 1 hour before. The results revealed a significant reduction of plaque accumulation and bleeding signs under herbal extracts in contrast to the placebo preparation. The salivary pH values were shifted to the alkaline range in the herbal extract group whereas the placebo product showed the opposite effect. Our data demonstrate the usefulness of herbal extracts as an adjunct in the treatment of periodontal disease and in a routine preventive regimen.