Our health system implemented a novel clinical decision-support system to reduce unnecessary duplicate nasal methicillin-resistant Staphylococcus aureus (MRSA) polymerase chain reaction (PCR) orders. In an 8-month period, the rate of duplicate MRSA PCR orders within 7 days declined from 4.7% (370 of 7,861) to 1.2% (120 of 9,833).