Background: Menstrual irregularities are a prevalent concern among females of reproductive age. These irregularities create great anxiety among female students and their families. Since, the students' physical, psychological and social well-being as well as quality of life may be negatively affected by menstrual problems. Irregular menstruation may be related to a wide variety of factors that could be prevented or managed to improve menstrual health. Aim: To identify the factors associated with menstrual irregularities among female nursing students at Damanhour University. Design: A descriptive cross sectional research design was utilized to conduct this study. Setting: This study was conducted at all scientific departments at Faculty of Nursing, Damanhour University, Egypt. Subjects: Proportional allocation method by academic year was used and female students (n=365) who met the inclusion criteria, conveniently selected from the first, second, third and fourth academic years at the Faculty of Nursing, Damanhour University 2022-2023. Tools: Three tools were used. “A structured interview schedule", “Factors associated with menstrual irregularities questionnaire" and “The Perceived Stress Scale". Results: The results of this study revealed a high prevalence of menstrual irregularities among female nursing students specially dysmenorrhea and premenstrual syndrome. A significant relation was found between menstrual irregularities and their dietary habits, exercise, daily sleeping hours, a time for relaxation, exposure to passive smoking and stress level. Regarding the multivariate analysis, the most risk factors among the previous statistically significant factors were stress (p=0.025) followed by body mass index (p=0.026) and sometimes having breakfast (p=0.040). Conclusion: The finding of this study concluded that menstrual irregularities were associated with a variety of factors. Furthermore, there was a high statistically significant correlation between multiple menstrual irregularities and stress, body mass index and skipping breakfast. Recommendations: Conduct frequent educational programs and a series of workshops on menstrual irregularities for health care providers, female nursing students and young females in the community to increase their awareness about menstrual health.