This paper is focused on actual and potential applications of mutanases as enzymatic dental plaque control agents in vitro and in vivo. All studies reported so far have demonstrated that mutanase was effective in preventing dental caries, suppressing the glucan-dependent adherence and the accumulation of microorganisms in dental plaque, and removing biofilms from dentures. In addition to their potential usefulness in dentistry as oral therapeutic agents, alpha-(13)-glucanases might be applicable to investigations of alpha-(13)-glucosidic linkages occurring in microbial cell-wall structures and glucans of certain higher plants. alpha-(13)-Glucanases obtained in a pure form are invaluable tools for studying the chemical structures of carbohydrates. Most promising prospects for the practical applications of alpha-(13)-glucanases in biocontrol of phytopatogenic fungi, as well as in efficient production of fungal protoplasts, are also discussed.