Objective To examine the change of epidermal growth factor（EGF）concentration in saliva of recurrent aphthous ulcer（RAU） patients during the ulcerous and interval period and epidermal growth factor receptor（EGFR） in ulcer biopsy samples. Methods EGF data of the samples, which were 27 saliva samples from RAU gained not only in the ulcerous period but also in interval period and 33 ones from normal persons, were acquired through enzyme linked immunosorbent assay（ELISA） and EGF standard curve. EGFR- RNA date of RAU biopsies, which were 31 biopsy samples from RAU got during the ulcerous period and 35 ones from normal persons, were surveyed by QF- RT- PCR. All RAU samples were obtained under the same level, which were the whole patients were minor aphthous ulcers and their ulcers occurred not over the first four days. All patients and normal persons were selected seriously under the rule of physical situations without any other diseases and histories of using medicines. Results The EGF concentration of saliva in RAU group at ulcer occurrence was higher than that in the interval period and the normal control with a significant test（F=3.24, P
