Purpose: The purpose of this study was to examine the perceptions of medication error including reporting among nurses and physicians. Methods: The participants were 244 nurses and 64 physicians working in a single hospital. The data were collected using questionnaires from August 25 to 29, 2008. Results: Nurses and Physicians perceived equally that the main causes of medication errors were ``confusion between 2 drugs with similar names`` and ``miscalculation the dose``. But nurses were more constituted in that the main cause of medication error was the ``prescription the wrong dose by physician`` by comparison with physicians` perception(being tired and exhausted). The classifying and reporting about 5 particular scenarios as medication errors also differed between and within scenarios according to the harm on patient and their situations. Participants were more likely to agree that the had no clear knowledge of what to report and how to report, especially nurses were highly perceived the fear of criticism and stigma as reporting barriers. These barriers would be remediable through construction of a reporting system and anonymous reporting. Conclusion: The study findings can be used in program designed to prevent medication errors and reduce or eliminate barriers to reporting.