Background: Drug administration is a main duty of a nurse’s clinical role. It involves great risk in patients’ lives and can potentially cause great harm. Despite many safeguards, preventable medication errors still occur. The aim of this descriptive quantitative study is to explore geriatric nurses’ perceptions of medication errors, perceived causes and their reporting behaviours. Methods: A self- report standardized survey was used to collect data from a purpose sample of nurses (n=17) working on geriatric wards at the Montfort hospital located in the province of Ontario. Data entry and analysis were done by using Statistical Package for the Social Sciences (SPSS) version 12 and presented using frequencies, number and percentage. Results: The most frequently identified causes of medication errors were failure to check patient’s name band with the patient’s medication administration record (MAR), nurses' tiredness, illegible physician handwriting, and nurses’ miscalculations of medication doses. In general, nurses were usually sure of constitutes a medication error and when to report it. However, only 30% of errors were perceived by nurses to be reported to the nurse manager. More than half (64.7%) of participants perceived that, some errors are not reported because nurses are afraid of the reaction they will receive from the nurse manager and the majority of them will notify the physician than to complete an incident report. Conclusion: Recognizing a medication error is the first step to reduce report and eliminate them, especially in acute care settings. Finding suggests that nurses need more educational reenforcement as to various issues related to medication errors, particularly defining and reporting these errors. Furthermore, the introduction of hospital policies and the development of structured protocols on drug administration may decrease medication errors. The hospital administration system needs to stress the importance of reporting errors and adopt a non-punitive approach to safeguard patient safety.