Premenstrual dysphoric disorder (PMDD) is a female psychiatric disorder affecting the behaviour, cognitive abilities, mental health status and academic performance of female students. It includes: mood symptoms, behaviour symptoms and physical symptoms. Aim: To assess phenomenology, measure the prevalence of PMDD among university students and assess the relationship between PMDD and socio-demographic and personality characteristics. Setting: This study was conducted at Zagazig University, Sharqia Governorate, Egypt. Methods: A cross-sectional study was conducted from September 2020 to December 2020. It included 755 university students. They filled several questionnaires covering Diagnostic and Statistical Manual of Disorders (DSM-5) criteria to diagnose PMDD, socio-demographic, menstrual factors, physical activity and personality traits. Results: Premenstrual dysphoric disorder was found in 159 out of 755 students (21.1%). Overall, the most frequently reported premenstrual symptoms were overeating/food cravings (84.2%), fatigue/lack of energy (83.6%), depressed mood/hopelessness (82.0%) and hypersomnia (78.9%). Binary logistic regression model revealed that significantly related PMDD risk factors include: being a medical student, having a duration of menstrual bleeding ≥ 7 days, the average length of one cycle ˂ 28 days, high menstrual blood loss, presence of dysmenorrhea and positive family history of premenstrual syndrome (sister/mother). Regarding personality traits, low extroversion and agreeableness, and high neuroticism were also significant PMDD risk factors. Conclusion: Prevalence of PMDD was high among university students, especially medical students, and it can have a detrimental effect on both academic life and educational accomplishments, quality of life and daily living activities