Skimmilk was inoculated with Salmonella typltimurium (approximately 103/ml) and with Streptococcus cremoris, Streptococcus lactis, mixtures of S. cremoris and S. lactis, Streptococcus diacetilactis, Streptococcus thermophilus, Lactobacillus bulgaricus, mixtures of S. thermophilus and L. bulgaricus, a mixture of L. helveticus and S. thermophilus, and Leuconostoc citrovorum. Inocula of lactic acid bacteria ranged from 0.25 to 5.0% and incubation temperatures from 21 to 42 C. Streptococcus cremoris, S. lactis, and mixtures of the two repressed growth but did not inactivate S. typhimurium during 18 hr of incubation at 21 or 30 C when the lactic inoculum was 0.25%. An increase in inoculum to 1% resulted in inactivation of S. typhimurium at 30 C by some of the mixed cultures. Both S. diacetilactis and L. citrovorum were less inhibitory to S. typhimurium than were S. cremoris or S. lactis. When added at the 1% level, Streptococcus thermophilus was more detrimental to S. typhimurium at 42 C than was L. bulgaricus. Mixtures of these two lactic acid bacteria, when added at levels of 1.0 and 5.0%, caused virtually complete inactivation of S. typhimurium during the interval between 8 and 18 hr of incubation at 42 C.