Abstract: It was hypothesized that serum level of immunoglobulins may play a role in the pathogenesis of oral mucosal diseases but little is known about the role of salivary immunoglobulins in the pathogenesis of these diseases. The aim of this study was to investigate the possible alterations in salivary immunoglobulin A (IgA-s) level in patients with oral aphthous ulcers and its relation with clinical parameters. Level of IgA was measured by "ELISA" test in the resting whole saliva of 24 patients with acute Recurrent Aphthous Ulceration (RAU) and during remission and the results were compared with 24 healthy volunteers. IgA was increased in acute RAU in comparison with healthy controls. Results demonstrated a significant increase in salivary IgA level in active lesions in relation to quiescence phase. No differences were found in salivary IgA level between major and minor acute RAU and other clinical parameters. The results of our study suggest a possible role of mucosal immune system in the pathogenesis of these lesions. It is reasonable to postulate that modulation of salivary immune system in vivo or production of immune materials in vitro can be efficient in the prevention or control of aphthous lesions.