A study was carried out at the Department of Biology, Addis Abeba University, in 1991 to determine the inhibitory potential of fermenting tef and the lactic acid bacteria isolated from fermenting tef dough on Salmonella spp., Pseudomonas aeruginosa, Klebsiella spp., Bacillus cereus and Staphylococcus aureus. The test bacteria grew in the fermenting tef uptill 30 hr or till the pH dropped to 4.7. Thereafter, growth was inhibited and decreases in population were apparent. The results showed that the spent media from all of the four lactic acid bacterial isolates, namely, Lactobacillus spp., Pediococcus spp., Leuconostoc spp. and Streptococcus spp. inhibited the test bacteria. Acidity on its own was not responsible for the inhibition of the test bacteria. The spent medium from Streptococcus spp. showed the best inhibitory activity amongst the lactic acid bacteria.