The Oxoid PBP2' latex agglutination test (OLA; Oxoid, Basingstoke, England) was evaluated in a controlled prospective study examining Staphylococcus aureus from 25 positive blood cultures. Subcultures of positive blood cultures with coagulase-positive, gram-positive cocci in clusters were batched, and the OLA was performed at the end of the working day, once growth was seen on the plate. Results were sent to the infectious disease pharmacist for therapy evaluation, and the 24-hour minimum inhibitory concentration (MIC) was confirmed the next day. Blood culture OLA results correlated 100% with oxacillin MIC results for the patient, and results were available in as little as 3 hours after the blood culture was positive. The mean time difference between the OLA and MIC reports was 19.4 hours. This test allowed same-day resistance marker reporting and was easily incorporated into the work flow of the clinical laboratory.