The relative efficiency of 15 selective media for enumerating unheated and sublethally heated strains of Staphylococcus aureus was tested against tryptic soy agar (Difco). Baird-Parker's egg yolk tellurite glycine pyruvate agar was found to be the medium of choice for both unheated and sublethally heated cells. Tellurite polymyxin egg yolk agar and egg yolk azide agar also gave favorable results. For unheated cells, Vogel-Johnson agar and tellurite glycine agar gave satisfactory results, but after heat treatment, even after a 10-h enrichment in tryptic soy broth for resuscitation of the heat injury, these media gave unreliable counts. Egg yolk acted not only as a diagnostic, but also as a protective agent in selective media for staphylococci. The protective action of egg yolk was more effective in azide- and tellurite-containing selective media than in salt-containing selective media.