Occurrence and spread of methicillin-resistant Staphylococcus aureus (MRSA) has become a major problem worldwide. The majority of hospitals in Switzerland have not so far been affected by this epidemic. We report two out-breaks of MRSA transmission in the surgical intensive care unit at the University Hospital of Geneva and show the possible inter- and intrahospital dissemination of MRSA. Evidence for cross-infection is confirmed by epidemiological investigation and molecular typing. Infection control measures and general precautions are necessary to halt further spread of MRSA.