Background: Safety during patient hospitalization is the patients' right, and the priority of health professionals. Also, a healthcare free from risks and failures is a goal that should be reached by health professionals and a commitment of professional education. Therefore, changes to the nurses' work environment need to focus on enabling and supporting nurses to provide high-quality and safe care Aim: of the study is to develop environmental and patient safety guidelines for nurses in critical care units. Design: the methodological design was conduct to achieve the aim of the current study. Setting: The study was carried out at critical care units of three university hospitals. Subject: the proposed guidelines was distributed to convenient sample of 31 jury members to test its validity and distributed to convenient sample of 162 participant divided to 88 bedside nurses and 74 resident physicians to test the reliability of the proposed guidelines. Results. The proposed guidelines' items were increased to 144 items, and sub-categorized to 17 dimensions. Conclusions: the validity and the reliability of the proposed guidelines were satisfactory, where it can be used in critical care units. Recommendations: use the developed environmental and patient safety guidelines in different critical care units in the selected hospitals and establish a safety committee to facilitate the application of environmental and patient safety committee.