Background and Objectives:Premenstrual syndrome is defined as a group of physical and psychological symptom, which happens during luteal phase of the menstrual cycle. Researches have indicated that premenstrual syndrome has significant effects on mental health and well-being of women. The purpose of the present study was to investigate the prevalence and severity of premenstrual syndrome and its relationship with psychological well-being in the students of Qom University of Medical Sciences. Methods:In this descriptive-correlational study, a total number of 226 female students of Qom University of Medical Sciences, were selected using convenience sampling method during 2017-2018. The participants were asked to respond to the Premenstrual Syndrome Scale, Ryff Psychological Well-Being Scale, and demographic checklist. Data were analyzed using descriptive, correlation, and multivariate regression statistical techniques. Results:In this research, 37% of the students reported mild symptoms, 49.8% moderate symptoms, and 13.2% severe symptoms of premenstrual syndrome. Pearson correlation coefficient test also showed that symptom severity had a significant correlation with psychological well-being (p<0.01), which could predict 11% of psychological well-being variance. Conclusion:The results of the current study revealed that premenstrual syndrome has a high prevalence in female students. Moreover, premenstrual syndrome is an appropriate predictor of psychological well-being in female students.