Recurrent aphthous stomatitis (RAS) symptoms usually painful and sometimes incapacitating. This condition is severed by recurrent characteristic and many efforts are conducted to encounter these things, but the results are still not satisfying. The etiology of RAS is still uncertain, however it is suggested that there is a correlation between the occurrence of RAS in women in their menstruation and premenompause period where there is noted decrease of estrogen. This article reports a case of RAS in a 50 year old woman who have suffered RAS for a year and become more severe in relation to the menstrual cycle especially pre menopause period. After estrogen administration the lesion is healed. This case brings attention to the clinicians, that it is important to know the estrogen level of RAS patients who are in premenopause period so they will receive an appropriate therapy.