Medication errors genuinely influence patient safety, staying cost in hospital and integrity of nursing job, because the nurses play a specific part in managing the medication for the patients. Accordingly, the exploration of the reason, which can cause medication errors from their opinion can be a powerful tool to recognize errors and instruct the proper procedures for preventing them. This project aim to investigate factors associated with nurses’ medication errors in a number of medical institutes (Ministry of Health) and the role of clinical pharmacist in these errors. The present project was cross-sectional study based on standardized questionnaire which was designed and distributed to the target nurses in a number of medical institutes (Ministry of Health). The target number was (171) depend on the calculation of sample size after the questionnaires were gathered; data were analyzed by the use of SPSS 24. The highest mean score was obtained in the factor related to medication packaging reason by 82.7%. The second group of reasons was system associated by 60.5%. The third reason was pharmacy associated by 45.3%. Documentation issues were the fourth reason by 39.5%. The physician-nurse issue was classified as the fifth and last group of why medication errors happen by 38.9%. The data of this project suggested the ranking of five reason of why medication errors happen: medication package reason, system reason, pharmacy reason, documentation-transcription reason and physician-nurse reason. All the medical field staff play a critical role in preventing these errors .Furthermore, clinical pharmacists must improve the nurses’ knowledge of how these factors will lead to critical errors and help them discover strategies to prevent these errors from happening.