[wpfilebase tag=file id=126 /]Lactobacillus crispatus ATCC 33820 and  L. gasseri ATCC 33323 were grown in MRS broth (pH 6.5) at 37ºC for 24 h and the antibacterial activities of cell free culture supernatants were determined by the agar well diffusion method. The culture supernatants were inhibitory to  Escherichia coli,  Klebsiella pneumoniae,  Pseudomonas aeruginosa,  Bacillus subtilis,  Staphylococcus aureus,  Enterococcus faecalis,  Pediococcus acidilacticii, and  Lactobacillus helveticus. The supernatants did not show any lysozyme activity. Addition of catalase did not affect the antibacterial activities of the supernatants. The antibacterial substances were heat stable (100ºC for 60 min) and sensitive to proteases.