As part of the Polish external quality assurance scheme, clinical laboratories were asked to send five consecutive isolates of Staphylococcus aureus and the corresponding susceptibility results to the national Centre of Quality Control in Microbiology. Of 1376 isolates submitted as S. aureus from 276 medical centres, 13 (< 1%) had been misidentified by local laboratories. Of 181 (13.5%) methicillin-resistant S. aureus (MRSA) isolates, most were identified correctly (c. 98% of laboratories). Although all MRSA isolates were fully susceptible to vancomycin, teicoplanin and linezolid, they were usually multiresistant; almost 23% were resistant to seven antimicrobial agents. Most (> 90%) MSSA isolates were susceptible to the tested antibiotics, except penicillin (21% susceptible) and tetracycline (62.4% susceptible). In addition to evaluating the proficiency of testing by local laboratories, the study yielded valuable information regarding the susceptibility patterns of S. aureus isolates in Poland.