Background: Acute poisoning is a major health problem leading to emergency department admission. Nurses' performance play an important role in the management of acute poisonings. Aim: This study aimed to evaluate the effect of educational guidelines on nurses' practice level regarding care for patients with acute poisoning in emergency unit. Study design: A one group quasi-experimental research design, with pre and post-test was utilized in this study. Setting: The study was conducted at poisoning treatment center affiliated to Ain Shams University Hospitals. Subjects: A convenience sample of all available nurses (30) caring for patients with acute poisoning. Data collection: The study data were collected using the following two tools: Tool (1): Nurses' demographic characteristics and Tool (2): Nurses' observational checklist. Results: The present study revealed that there was a highly statistically significant difference between level of nurses' practice pre, post implementation of the educational guidelines. Conclusion: The implementation of the educational guidelines has a positive effect on nurses' practice level regarding care for patients with acute poisoning in emergency unit. These findings support the research hypothesis. Recommendations: Regular continuous nursing educational program at least every six months should be implemented for enhancing and updating nurses' practice about nursing care offered to patients with acute poisoning in emergency unit, to achieve high quality of care.