Background:  Postpartum bleeding is one of the most serious emergencies which nurses face.  Aim of the study: To evaluate the effect of educational guidelines on maternity nurses' competencies regarding prevention and controlling of primary postpartum hemorrhage. Design: Quasi experimental research design. Setting: This study was carried out in Minia University for maternity and children hospital. Sample: Convenience sample consisted of 50 maternity nurses units who provide direct nursing care for women during labor and immediate post-partum period. Tools: four tools were used to fulfill this study (tool I: A structured self administered questionnaire, Tool II: Knowledge questionnaire, Tool III: Competency performance checklist (Observational Checklist), Tool IV: Maternity Nurses attitude scale regarding prevention of primary postpartum hemorrhage). Results: All knowledge, practices and attitude related items showed a statistical improvement (86%,83% and 88% respectively) after the intervention (P=0.001*). A positive correlation was found between maternity nurses' knowledge and their practices with a high statistical significant differences (P. value < 0.00). Additionally, there was a positive relation between studied nurses' practices and their attitude with a high statistical significant differences where p_ value was 0.01. Conclusion: Competency nursing intervention were effective in improving knowledge, attitude, and performance level of maternity nurses regarding the prevention and controlling of primary PPH. Recommendations: Provide competence-based standards and guidance for maternity nurses' knowledge and practices.