A Lactobacillus sake strain (L. sake 2a), isolated from Brazilian sausage ('lingüiça'), possessed antilisterial activity. The inhibitory activity observed in culture media was due to a proteinaceous compound, as demonstrated by the sensitivity to proteolytic enzymes. Inhibition due to hydrogen peroxide, organic acids and lytic bacteriophages was ruled out. The inhibition of Listeria monocytogenes by L. sake 2a was also demonstrated in laboratory-prepared 'lingüiça'. After four weeks at 8 degrees C, counts of L. monocytogenes in the pork product co-inoculated with L. sake 2a were about 6 log10 lower than those in control samples containing only L. monocytogenes. These results suggest that L. sake 2a strain produces a bacteriocin-like substance that can be used to inhibit the growth of L. monocytogenes on Brazilian sausage.