Critically ill patients are among the most vulnerable groups that exposed to pressure ulcer because of limited physical activity. Aim: To evaluate the effect of nurses' compliance to evidence-based guidelines on pressure ulcers prevention for critical patients. Design: A Quesi experimental research design (pre- and post-test). Sample: A purposive sample of (55) nurses who agreed to participate in the study. Setting: The study was carried out at four intensive care units (Cardiothoracic, Neurological, Urology, and Trauma) that were affiliated to Minia University Hospital. Tools: Two tools were used for data collection prepared by the researcher. First tool: Structured questionnaire sheet, includes two parts, 1st Part: Nurses' structured interview sheet about socio-demographic data, 2nd Part: Knowledge Assessment Questionnaire Sheet about pressure ulcer. Second tool: Pressure ulcer guidelines checklist for practice covered the following items regarding PUs (Maintenance of skin integrity, Skin care and prevention of urinary incontinence). Results: Nurses' knowledge and practice were statistically significance difference at the pre-test (before education three months) which lead to low compliance and at I (post-test) and II (follow-up) (after three months from education) that improve nurses' compliance presented by P value (0.000). Conclusion: nurses' knowledge and practice improved after receiving education about the evidence based guidelines and their compliance was improved at the post-test I and II. Recommendation: continuous education and training sessions for all nurses working at different intensive care units about pressure ulcer preventive guidelines to improve their knowledge and compliance.