The following article reviewed 157,483 clinical decision support (CDS) alerts on 2,004,069 medication orders, in order to examine the override rates for medication-related CDS alerts in the outpatient setting, the reasons cited for overrides at the time of prescribing, and the appropriateness of overrides. Results show that the most common alerts were duplicate drug, patient allergy, and drug-drug interactions. An average of 53% of overrides were classified as appropriate, and rates of appropriateness varied by alert type from 12% for renal recommendations to 92% for patient allergies.