Aim of the study: The present study aimed to assess incidence of menstrual disorders and its effect on students' academic performance. Study design: A descriptive study was utilized. Type of sample: A convenient sample. Study subject: The study was conducted among 986 undergraduate females students enrolled on 1 st , 2 nd , 3 rd and 4 th grade. Study setting: This study was conducted at the Faculty of Nursing, Mansoura University. Tools of data collections: Fifth tools were utilized such as(structured interviewing questionnaire schedule, pictorial blood assessment shart, simple descriptive pain intensity scale, premenstrual and premenstrual dysphoric disorder questionnaire and assessment tool to determine the effect of menstrual disorders on academic performance)Results: The current study results revealed that the majority of nursing students complained from dysmenorrhea followed by menorrhagia in more than one third of them , less than quarter of them had secondary amenorrhea and more than tenth of them had premenstrual syndrome. There was a significance relation between different types of menstrual disorders and academic performance. Conclusion: This study concluded that menstrual disorders were common among students in the Faculty of Nursing which affect their academic performance in forms of lectures absence, loss of concentration and understanding, sleeping desire during lectures in addition to affecting the practical performance of the students. Recommendation: Health programs should be conducted for young women about menstrual disorders and its proper interventions to alleviate it.