The commercial 'pure' oleuropein and phenolics extracted from olives inhibited the growth and enterotoxin production by Staphylococcus aureus S-6 in broth as well as in reconstituted milk (model food system). It was found that the inhibition of this organism in N-Z amine A broth was influenced by the initial inoculum size, the pH of the media, and the concentration of additive. In particular, growth and enterotoxin B production by S. aureus were inhibited in broth with a high concentration of oleuropein (0.6%). The inhibition was more pronounced in samples with low pH and low inoculum size. In the case of milk, enterotoxin B production was also influenced by the initial concentration of extract.