Performance of external quality control is an important tool for monitoring results of susceptibility testing in microbiology laboratories. The aim of this study was to assess the ability of Iranian microbiology laboratories for detection of MRSA and performance of susceptibilitytesting. One strain of Staphylococcus aureus (ATCC 33591) resistant to methicillin and susceptible to vancomycin were sent to clinical microbiology laboratories. This isolate was blinded –coded, and laboratories were asked for  identification  unknown strain and susceptibility testing it to methicillin, vancomycin chloramphenicol , erythromycin and tetracycline by using their  standard disk diffusion method   guidelines Of 2282 laboratories contacted, 1509(66.1%) agreed to participated in our study and sent back their results on time for analysis. Regarding to identification of S.aureus of 1509 laboratories, 1283(85%) were able to identify isolate to genus and species level. Of 1509 laboratories 1349 (89.4%) performed correct susceptibility testing for methicillin, 88 laboratories  (5.8%) could not determined resistance of S.aureus to methicillin and 72(6.8%) laboratories did not performed susceptibility testing of S.aureus for methicillin. Of 1509 laboratories, 889 (58.9. %) correctly performed susceptibility testing of S.aureus to vancomycinn and reported correct result. while 594( 39.4%) laboratories reported incorrect results,26 (1.7%) laboratories did not performed susceptibility testing to vancomycin. In conclusion our study revealed that detection of MRSA in clinical microbiology laboratories is satisfactory but the majority of laboratories (about 40%) have difficulties in performance of susceptibility testing of S.aureus to vancomycin.