Background: Classic recurrent aphthous stomatitis is a localized condition representing a relatively simple disease, although a minority of patients may be predisposed to it by systemic conditions or diseases. Aim of the study: To evaluate the level of basic awareness of various risk factors ofaphthous ulcer among dental students in Qassim Province. Subjects and Methods: A cross-sectional qualitative study recruiting dental students from three dental colleges in Qassim province. A total of 190 dental students participated in the study. Each participant was given a self-administered questionnaire to solve on the spot. The questionnaire investigatedthe basic knowledge of recurrent aphthous stomatitis; the way of management and awareness of predisposing factor that may provoke the ulcer.Respondents were graded on a four-level scale as poor, fair, good and excellent. Results: A total of 39 female respondents (40.6%) had excellent awareness, while males students only 11 (11.7%) were having same level of awareness regarding RAS. On the other hand the highest percentage of males 35(37.2%) had good awareness and for females 35(36.5%) had good awareness with highly significant difference between both groups (p<0.001). Conclusion: The study showed that the female dental students have better level of awareness regarding RAS in than male dental students. The study also reveals that the higher academic years have higher degree of awareness regarding RAS.