In this case-control study, recent stress and trait anger/anxiety of otherwise healtlhy patients with active recurrent aphthous stomatitis were compared to those of dental patients with no history of RAS (controls). RAS group reported more angry/anxious feelings than controls (2.11 +/- 0.38/1.84 +/- 0.30, respectively; p < 0.001), and more recent stress (2.81 +/- 1.36/1.96 +/- 1.02; p < 0.01). Among subjects with high angriness/ anxiety, RAS subjects showed higher stress level (p < 0.005). The study revealed that anger/anxiety level mediates the relationship between stress level and RAS.