Background and aim: Irritable bowel syndrome (IBS) is a common functional gastrointestinal disorder and is the most commonly diagnosed one by gastroenterologists. In this study, we aim to explore the frequency of IBS among medical students in Qassim, and the factors associated with this disorder among them. Materials and methods: A cross sectional study was carried out among medical students of all academic levels in three local universities in Qassim region; Qassim University, Unizah as well as Alrajhi colleges of medicine. Data for the study were collected throughout the 1st semester of the academic year 2015-2016 using a validated, self-administered, and anonymous paper questionnaire. The questionnaire included three main sections: Demographics, Rome III criteria and hospital anxiety and depression scale (HADS). Results: Among 511 students completed the study and of those 70 (13.7%) had IBS. Senior medical students are 3.61 times more likely to have IBS than juniors (p<0.001). Depression was significantly associated with IBS (p= 0.042). Stepwise logistic regression showed that chronic health problems, more advanced academic level and personal history of IBS were significant predictors for IBS. Conclusion: The prevalence of IBS is 13.7% among medical students in Qassim region. Depression, age, living situation, advanced academic years, family or personal history, or an episode of travellers' diarrhoea were the main predictors of IBS. Offering psychological and emotional support along with stress management courses in order to deal with stress is recommended.