Introduction: Recurrent aphthous stomatitis (RAS) is a common clinical condition producing painful ulcerations in the oral cavity. However, there has been no optimal therapeutic approach. Topical and systemic steroids commonly prescribed for the condition have local and systemic side-effects. Recently, there is growing tendency toward herbal medication in the modern society. The objective of this study was to assess the efficacy of a chamomilla mouth rinse on reducing the signs and symptoms of aphthous lesions in comparison with a placebo mouth rinse. Material and Methods: A randomized, triple-blind, placebo-controlled trial was performed on 36 patients, from cases diagnosed with RAS, attending the Department of Oral Medicine, Mashhad University of Medical Sciences. They were randomly divided into two groups: the intervention group(A), receiving chamomilla mouth rinse, and the control group (B) receiving a placebo rinse. The ability of the solution to control the pain and burning sensation and the number and size of the ulcers were evaluated. Results: The number of ulcers in the 3 rd visit (four days after treatment) showed a significant difference between the groups ( P <0.001). The pain and burning sensation (VAS) was reduced significantly in the test group in the 2 nd ( p =0.001),3 rd and 4 th visit ( P <0.001). Conclusions: Chamomilla mouth rinse was effective in the treatment of RAS, controlling the pain and burning sensation without producing any adverse side effects and can be advised as an alternative RAS treatment.