Six culture media were compared with blood agar regarding colony counts and colony diameters of 53 Staphylococcus aureus strains. There were no statistically significant differences between the media. The forced differentiation of the results via cluster analysis, however, gave some indications that differences existed. In terms of colony counts, LSM, BP Oxoid and BP Oxoid + pp gave results similar to those given by blood agar. Colony diameter seemed to be a doubtful measure of the media's suitability and none of the six media showed similar diameter values to those of blood agar. As regards the appearance of the S. aureus strains on the six media, BP BBL and LSM corresponded the most closely to the inventors descriptions. The selectivities of the media were tested by cultivating 102 food samples from various sources. The most favourable retardation against micro-organisms other than S. aureus was shown by BP BBL, KRANEP and LSM. In terms of all tests performed, BP BBL was the most satisfactory medium for isolating S. aureus. PCVJ was the poorest of all media used in this study.