Background: Abnormal uterine bleeding (AUB) is one of the most serious problems that face females all over the world not only through their reproductive age but also after menopause. The International Federation of Gynecology and Obstetrics (FIGO) described and published the PALM-COEIN classification, which classify the underlying etiologies of (AUB). Aim: This study aims at assessing nurses' knowledge about the (PALM-COEIN) classification system for AUB. Methods: Descriptive cross sectional design was used. Setting: The hospital for obstetrics, gynecology, and pediatrics in Assiut city. Samples: A convenient sample of 100 nurses were involved. Tools: The researcher designed a self-administered questionnaire. Results: The percentage of nurses who had satisfactory and inadequate understanding of the (PALM-COEIN) categorization system for AUB was approximately 38% and 62%, respectively. There was a statistically significant difference between the investigated nurses' overall knowledge level and educational background. Conclusion: Most of the studied nurses had unsatisfactory knowledge about the (PALM-COEIN) classification system for AUB. Recommendations: maternity nurses should be encouraged to participate in an educational program regarding the (PALM-COEIN) classification system for AUB in order to enhance their knowledge and nursing care.