Background: Medication error (ME) is any preventable event in the treatment process that may lead to inappropriate medication use or cause harm to the patient.1 Emergency Department (ED) is usually the most frequently visited department of an hospital and more medication error prone.7,9 The frequency of medication errors varies from 4%-39% in different Emergency department settings.10,11 Material and Methods: It’s a prospective cross-sectional observational study, done in the emergency hospital of a tertiary care hospital, Islamabad during two months duration. A total of 928 patients were evaluated, to see the medication errors while administering the prescribed drugs. Prescribed drugs were evaluated with the help of healthcare providers. Data was put and analyzed in SPSS 16. Results: Among 928 patients 535 (57.6%) were males and remaining 393 (42.4%) were females. 66 (7.1%) out of 928 patients had some kind of medication error. Among 66 patients, 10(15.2%) were given medications incorrectly (identity error), 40 (60.6%) had dose medication error, 8 (12.1%) patients were given incorrect dosage form, 7 (10.6%) patients were given through incorrect dosage route and only 1 patient had frequency medication error. Conclusion: The frequency of medication errors was 7.1%, Majority of errors were due to improper dose formation and administration, than wrong patients, dosage form and dosage route. Although, studied patients didn’t have adverse effects of these errors.