Betamethasone 17-benzoate is a representative steroid, which can be used in the treatment of recurrent aphothous ulcers (RAU). In Vitro: Betamethasone 17-benzoate is the topical steroid^[1]. Betamethasone 17-benzoate is a local corticosteroid^[2]. A double-blind study of the effectiveness of Betamethasone 17-benzoate in the treatment of recurrent aphothous ulcers (RAU) is concucted. Betamethasone 17-benzoate is found to be effective in reducing symptoms and shortening healing time but not in preventing recurrences^[3].