Abstract Introduction: Medication administration error reporting has been accepted as a basic attempt for the improvement of patient safety. The main objective of the study is to identify the barriers to reporting of the medication administration error among nurses. Methods: Descriptive cross sectional research design was used. All the registered nurses working on various inpatient units of Tribhuvan University Teaching Hospital, Maharajgunj, Kathmandu were taken as study population. Proportionate stratified random sampling technique was used to select 228 nurses. A structured questionnaire was used to collect data. The findings were entered into EPI DATA3.1 and transferred onto the statistical package for social science 16 version for further analysis. Data was analyzed and interpreted by descriptive; mean, median, standard deviation, frequency and percentages and inferential statistics; independent t test, one- way ANOVA. Results: Possible medication administration error was wrong dose (66.70%). Fear (1.76±0.36) and administrative response (1.46±0.39) related barrier was major barrier to reporting of medication administration error among nurses. It is observed that nurses who had less than five years of work experience present higher perception level regarding administrative response barriers in reporting MAEs. There is significant difference between disagreement over error related barrier and background variables such as age (p=.02, marital status (p=.01), work experience (0.006).Conclusion: In this study, fear and administrative response related barrier is present as most influential barrier to reporting of Medication Administration Error. So it is necessary to establish communicative environment in inpatient unit to reduce fear and provide positive reinforcement to encourage reporting.Keywords: barrier, medication administration error, reporting Introduction Patient safety is a concern worldwide and is a significant challenge facing healthcare systems today (1). Medication errors are one of the most important cause of injury in hospital settings (2), which extensively consume the financial resources of hospitals. Errors may occur during prescribing and administration phase of the medication leading to adverse effects on the health of the patients (3). In Ethiopia, the incidence of medication administration error is 56.4 percent (4) where in Jordan, the rate of medication errors reported to nurse managers was 42.10 percent (5). In Turkey, 41.60 percent of medication administration errors were reported among nurses (6). Medication error reporting is a basic effort for the improvement of patient safety and error reporting barriers considered to be one of the most important healthcare problems worldwide (7). Reporting errors is fundamental to error prevention. Study on barriers to reporting of medication administration errors (MAEs) in Nepal is still limited. Hence, the present study was undertaken to identify perceived barriers to reporting of MAEs among nurses.Methods This was a cross-sectional study conducted in Tribhuvan University Teaching Hospital (TUTH), Maharajgunj in Kathmandu to identify barriers to the reporting of medication administration errors among nurses. Nurses who had worked more than three months in different inpatient unit and have completed at least Proficiency Certificate Level with post of either staff nurse or in charge/sister, with having work experience of more than three months in the hospital were included in this study. Nursing Director, supervisor, senior supervisor and ANMs were excluded in this study. The sample size was determined by assuming the prevalence of barriers to reporting of medication administration errors among nurses to be 50 percent with an error of 5 percent, 95 percent confidence limit and non response rate 10 percent, the sample size was 228. A proportionate stratified random sampling technique was used to obtain the desired sample size from each stratum. All thirty one inpatient units were categorized in to eight units which were considered as stratum. Random number generated by Decision Analyst Stats TM 2.0 was used to select sample from each stratum. Researcher first of all was identifying the number of nurses working in respected units through the help of duty roaster. About ten to fifteen nurses were approached per day and 15-20 minutes were taken to fill the questionnaire. The researcher herself distributed self-administered questionnaire to selected nurses in each inpatient department of the hospital in order to prevent contamination of the data and gain feasibility. An elaborative briefing on questionnaire was done to each participant prior to fill the questionnaire. The completed data were collected by researcher herself. The time during the lunch break, after duty shift, and after medication was considered to fill questionnaire without having its impact on ward activities.A structured questionnaire was developed by the researcher based on the objective of the study. The reference was taken from Wakefield questionnaire for medication administration error survey 2005, Nurses’ perceptions of medication errors; Gladstone 2001. Pretesting of the tool was done to assess the clarity, feasibility, and appropriateness of tool among ten percent of sample size in Gandaki Medical College Teaching Hospital and Research Center Pvt. Ltd. (GMCTHRC), Pokhara. Ethical clearance was acquired from Research Committee of Pokhara Campus and Institutional Review Board of Tribhuwan University, Institute of Medicines at the beginning of the study. After obtaining written permission from the hospital authorities I approached the selected participants. The objective, duration, process and time of data collection were explained to nursing director, administrative officers and supervisors of TUTH. Nurses’ duty room was taken in order to collect the filled questionnaire from respected units. Informed written consent was taken from each of selected participant. The anonymity of the information was maintained. The participants were informed that there was no known risk. Nurses’ dignity was maintained by giving right to reject or discontinue from the study at any time during data collection. All information was obtained with confidentiality and obtained information was used only for the study purpose. Informal education regarding medication administration error and importance of reporting for patient safety was provided to the nurses. The data was collected from 2017/06/29 to 2017/07/28 in day time during lunch break from 12pm to 5pm. The response rate was 100%.Field editing and checking were done. The collected data were entered into computer using the software EPI-DATA 3.1 on the same day and entered data were transferred onto the statistical package for social science (SPSS-16 version) for further analysis. The descriptive analysis such as mean, standard deviation, median, frequency and percentage were used for identifying the respondents’ background variables, possible medication administration errors related variables and perceived barrier scale to reporting of medication administration errors related variables. Inferential statistics independent t test and one-way ANOVA were used to determine the difference between background variables and perceived barriers to reporting of MAEs.