In April 1982, a patient infected with methicillin-resistant Staphylococcus aureus (MRSA) was transferred to the Royal Perth Hospital from the Royal Darwin Hospital. Within three months, 19 patients and four staff members had become infected or colonized with MRSA. The outbreak was terminated only after all colonized inpatients were transferred to a separate isolation unit. After the outbreak, all new patients and new employees who had been in hospitals outside Western Australia in the previous 12 months were screened. From June 1, 1982, to June 30, 1984, 28 of the 649 patients (4.3%) screened on admission to the Royal Perth Hospital were found to be harbouring MRSA. During the same period only one of the 468 persons (0.2%) screened on application for employment at the Hospital was found to be colonized with MRSA. Since the policy of screening new patients and staff from hospitals outside Western Australia was introduced, no serious outbreak of MRSA has occurred.