Background: Critical Care Nursing is a specialized field of Nursing requiring focused knowledge and technical skills, compassionate care and skilful practice. This study was designed to develop and test Clinical Nursing Practice Guidelines (CNPG) for oral care of critically ill patients Methods: Clinical Nursing practice Guidelines were formed with evidence sources and consensus    from relevant stakeholders. Quasi experimental pretest posttest research design was used to assess the effect of CNPG on oral care practice of Nursing personnel. Data was collected with non participant observation. Results: Implementation of Clinical Nursing practice Guideline showed a significant difference in the oral care practice of nursing personnel. Conclusion: The study  highlights how evidence gathered from research studies can be translated into bedside care through Clinical Nursing Practice Guidelines. It  also shows the effect of the CNPG on practice of nurses.