The aim of this work was to study in the same microbiological conditions and for the first time the inhibitory action of eight class IIa bacteriocins against 23 Gram-positive bacteria in which some of them are industrially used as starters and against the eight class IIa bacteriocins producing strains themselves. The sensitivity of each strain was determined after MPA using the mathematical model described by Cabo et al. (1999, J. Appl. Microbiol. 87, 907-914). Therefore, the principal component analysis realized led to a strong correlation between spectrum and extra-disulfide bridge and a minor correlation between spectrum and isoelectric point of each bacteriocin.