The antagonistic potential of nonpathogenic Staphylococcus strains against Bacillus subtilis wild and type strains were studied under conditions simulating a paper- and board-machine environment. The antimicrobial activity was measured by growth inhibition in an automated turbidimeter. The antagonistic potential was compared with that of generally used chemical biocides in a paper- and board-machine environment. The siderophore-containing extracts of Staphylococcus strains significantly inhibited vegetative growth of B. subtilis and delayed the germination of spores both in synthetic and in white-water media. The mill strains were more resistant than type strain against Staphylococcus siderophores and against chemical biocides. The Staphylococcus siderophore-containing extracts did not interfere with the bacteriostatic effect of chemical biocides, but no synergy was detected. The results indicate the potential for application of Staphylococcus siderophore-containing extracts as biocontrol agents in paper- and boardmachine environment.