ObjectiveThis study was conducted to assess the magnitude and contributing factors of medication administration errors among nurses in federal hospitals in Addis Ababa, Ethiopia.DesignA hospital-based cross-sectional study design was employed. Data on medication administration and associated factors were collected using a structured self-administered questionnaire. Multivariable binary logistic regression analysis was done to identify factors associated with medication administration errors on the basis of adjusted OR with 95% CI and a p value less than 0.05.SettingThis study was conducted in federal hospitals in Addis Ababa, Ethiopia.ParticipantsFour hundred and twenty-three randomly selected nurses participated.Outcome measuresThe primary outcome variable is medication administration error, which was ascertained using the following errors: wrong medication, wrong dose, wrong time, wrong route, wrong patient, wrong drug preparation, wrong advice, wrong assessment and wrong documentations.ResultsA total of 59.9% (95% CI: 55.0% to 64.8%) of the nurses in the federal hospitals in Addis Ababa committed one or more medication administration errors in the last 12 months prior to the survey. The most commonly reported medication errors were wrong time (56.8%), wrong documentation (33.3%), wrong advice (27.8%) and wrong dose (20.1%). Medication administration errors among nurses were significantly associated with short work experience (adjusted OR (AOR): 6.48, 95% CI: 1.32 to 31.78), night shift work (AOR: 5.0, 95% CI: 1.82 to 13.78), absence of on-the-job training (AOR: 3.16, 95% CI: 1.67 to 6.00), unavailability of medication administration guidelines in wards (AOR: 2.07, 95% CI: 1.06 to 4.06) and interruptions during medication administration (AOR: 2.42, 95% CI: 1.30 to 4.49).ConclusionIt was found that a high proportion of nurses in federal hospitals committed medication administration errors. Short work experience, night shift work, absence of on-the-job training, unavailability of medication administration guidelines and interruptions during medication administration explained the high magnitude of medication administration errors.