In this research project, the response times to chest compressions, first defibrillation, and first dose of epinephrine in cardiac arrest were measured over a 3-month period through retrospective chart reviews. All nursing staff then participated in random, unannounced mock code blue drills using a high-fidelity patient simulator. After 3 months of code blue drills, the variables were again measured in patient code blue situations and compared with the response times before training. At the conclusion of this study, the response times for start of chest compressions and epinephrine administration improved significantly; the response time to defibrillation did not improve significantly. The response times were measured for an additional 3-month period to assess if the improvement was sustained.