Objectives: Stress and anxiety are controversial factors involved in the complex pathogenesis of Recurrent Aph - thous Stomatitis (RAS). The determination of salivary cortisol is a useful, simple and safe test to detect states of high stress or anxiety. The aim of this study is to check for changes in salivary cortisol levels in patients with RAS during periods of active disease. Study design: A measurement of cortisol employing Enzyme-Linked Immuno Sorbent Assay (ELISA) was car - ried out in samples of unstimulated saliva from 20 patients with active lesions of RAS and 10 healthy individuals used as controls. Results: Increased levels of salivary cortisol were detected in 3 cases, all of them within the group of patients with RAS. In none of the control group patients the level of salivary cortisol was increased. The mean level of salivary cortisol was 0.64 mg / dl (range 0.2 to 1.62) for patients with RAS and 0.57 mg / dl (range 0.25 to 1.09) for controls. Conclusion: Salivary cortisol levels are not statistically higher in patients with active lesions of RAS.