Major teaching hospitals in each state of Australia participated in five annual surveys (1986 to 1990) of clinically significant isolates of Staphylococcus aureus. All isolates of methicillin-resistant S. aureus (MRSA) were phage typed with the Basic International Set and an Australian experimental set of typing phages. One or two predominant strains were isolated in individual states during each of the survey periods. Less than 3% (33 of 1243) of MRSA isolates were not typable and more than 86% (1070 of 1243) belonged to strains that were isolated on at least five occasions during a single survey period. Strains of phage types 83A/85/95/90/88@47T/90A/87M/13M and 85/90/88@47T/90A/87A were the most prevalent, but each was identified in only four of the five surveys. Isolates of phage type (83A/85/95) weak/88@87M persisted throughout the survey period.