Otaka engyme (O.E.) is a campound of various enzymes extracted from the vegetables which are arbitraily chosen and there have been published reports on its curative effect of an inflammation of the oral mucosa as well as its bactericidal action. From these effects, its beneficial actions on inhibiting the deposition of plaque and preventing the cases of gingivitis can be reasonably expected.In the present study, the authors used high school girls by way of experimental subjects. A group of 39 girls, who had been given a previous training in a toothbrushing method, were instructed to use O.E. containing dentifrice and another group of 43 girls were instructed to use a placebo for a period of one week.The degrees of dental surface cleanliness and PMA indices before and after the experiments were examined and compared. There was observed a tendency of improvement in both of these areas in common with the experimental and control groups. But the experimental group was found to reveal a statistical difference. This fact is thought to have bearings on the O.E. dentifrice.