Recurrent aphthous stomatitis is one of the most common diseases of ulcerative oral mucosal lesions and its cause remains elusive. The purpose of this study is to evaluate the therapeutic effect of topical steroids for the treatment of recurrent aphthous stomatitis. We performed the study with 50 cases who had visited to our office for the treatment of recurrent aphthous stomatitis during the recent five years. We devided 50 cases into five groups. Group 1 is that triamcinolone of 0.1-0.2mg was injected into the submucosal lesions of ulcerations. Group 2 is that the gargling of 5ml with triamcinolone tablet of 2mg was used three times per day for seven days. Group 3 is that the gargling of 5ml with betamethasone tablet 0.5mg was used three times per day for seven days. Group 4 is that tetracycline gargling was used six times per day for seven days. Group 5 is that normal saline gargling was used six times per day for seven days. The retrospective analysis of results were as follows : Betamethasone gargling was effective in the treatment of minor aphthous stomatitis and the submucosal injection of triamcinolone was effective in the treatment of major aphthous stomatitis, but none of the different therapeutic methods was effective for herpetiform stomatitis. In the evaluation of mean recurrence periods, the triamcinolone gargling and betamethasone gargling showed longer asymptomatic periods than other methods. We concluded that some kinds of topical steroids can be used for the treatment of recurrent aphthous stomatitis but the proper selection of agents according to the type of the disease is important for the treatment.