The obstetric triage system is more specific since it considers factors like the state of labor, fetal health, testing, and interventions for obstetric issues. Aim: To evaluate the effect of implementing teaching guidelines regarding obstetric triage on nurses' performance. Design: A quasi-experimental design was used to conduct this study (pre/post-test). Settings: the research was carried out in the Emergency Labor and Delivery Unit at Mansoura University Hospital. Sample: non-probability convenience sampling technique was used to select the sample of the study. One group of nurses consisted of sum fifty nurses at three shifts working in the previously selected areas.Tool for data collection: A structured interviewing questionnaire: It included three parts; part 1 about nurses' characteristics, part 2 to assess nurses' knowledge regarding patients' triage system, and part 3 about Adapted Obstetrical Triage Acuity Scale (AOTAS). The Results:The effect of teaching guidelines on the total score of nurses' knowledge, their Reported performances (recording, procedures), response, and quality of care, that there is satisfactory knowledge post teaching guidelines. this study reveals that there are highly statistically significant differences between pre and post-teaching guidelines with a P-value <0.001. Conclusion: Based on the study findings, Triage application after teaching guidelines had positive, and efficient in improving nurses' knowledge and practices. Recommendation: Application standardized triage to improve patient care, improve outcomes, and improve staff competency through continuing education and development of clinical protocols in accordance with the rules and regulations.