Screening all hospitalized patients for MRSA (methicillin-resistant Staphylococcus aureus) is widely advocated, but the effectiveness of this practice was called into question by a high-profile negative trial. In contrast, this study found significant reductions in both colonization rates and rates of hospital-acquired infection caused by MRSA after institution of a universal surveillance program. The difference between the results of these studies highlights the difficulty of interpreting and applying evidence from clinical trials to patient safety efforts, as discussed in a recent editorial.