Methicillin-resistant Staphylococcus aureus (MRSA) is responsible for the largest outbreak of hospital-acquired infection (HAI) that the world has ever seen. It is not replacing methicillin-susceptible S. aureus (MSSA), but seems largely to be an additional burden of HAI with double the mortality of MSSA infections, at least in the bacteraemic form. It is often highly transmissible and carriage seems to lead to clinical infection much more frequently than with MSSA carriage. Additional screening for MRSA needs to be performed, not only to establish the size of the problem and to allow initiation of decolonization measures to prevent the onset of clinical disease, but also to allow implementation of infection control precautions that will be necessary to control the epidemic. MRSA is a huge clinical burden that is causing great public and political concern. Current treatments are suboptimal. Control measures are likely to be effective and cost saving if they have a broad enough base, and should be implemented without further delay.