Background: The term “aphthous” is derived from a Greek word “aphtha” which means ulceration. Recurrent aphthous stomatitis (RAS) is one of the most common painful oral mucosal conditions seen among patients. These present as recurrent, multiple, small, round, or ovoid ulcers, with circumscribed margins, having yellow or gray floors and are surrounded by erythematous haloes, present first in childhood or adolescence. Many studies have reported that stress and anxiety have a role in the onset and recurrence of aphthous ulcers. We aimed to do a study on association between apthous ulcer and stress.s Material and Methods: A cross sectional study was done on 100 medical students in Hamdard Institue of Medical sciences, New Delhi. Questionnaire contained questions about aphthous ulcers and questions on perceived stress by modified perceived stress scale. Statistical analysis was done using SPSS 20. Student t test and chi square test were used and a p value of <0.05 was taken as significant. Result: The prevalence of aphthous ulcers among medical students was high (60%). Majority participants (81.6%) showed high level of stress due to exams or some other reasons. Only 26.6% of participants showed positive history. Conclusion: The study revealed that there was a significant association between stress and apthous ulcer as was observed in medical students who are under constant pressure as compared to other professional students.