One of the factors involved in the pathogenesis of recurrent aphthous stomatitis (RAS) is a cell-mediated immune response in which several cytokines seem to play a major role. The aim of this study was to detect, enumerate and characterize T helper cells which are secreting type 1 cytokines (interleukin [IL]-2, IL-12, interferon [IFN]-γ, and tumor necrosis factor [TNF]-α) and type 2 cytokines (IL-4, IL-5, IL-6, and IL-10) in the peripheral blood of patients with RAS. Thirty-two patients in the active phase of RAS (14 men and 18 women) and 40 healthy individuals participated in the study. T helper (T) cells were detected and characterized using Elispot assay. T cells secreting IL-2, IL-12 or IFN-γ were increased in patients with RAS compared with the controls (p < 0.05, p < 0.001 and p < 0.001, respectively). T cells secreting TNF-α in RAS patients and controls were not statistically different (p > 0.05). T cells secreting IL-10 were increased in patients with RAS compared with the controls (p < 0.05). T cells secreting IL-4 were decreased in patients with RAS compared with the controls (p < 0.001), No statistical difference was observed between T cells secreting IL-5 or IL-6 in patients with RAS and controls. Our findings suggest that the increased numbers of T cells secreting type 1 cytokines may influence the immune response against RAS. Whether this action is of etiological importance or epigenetic phenomenon is a question that needs to be answered.