Lactobacilli have long been considered to be protective flora in the vagina. In this study, samples were taken from the lateral vaginal wall of 19 healthy women, and 58 strains of Lactobacillus spp. were isolated from 10 of these women. The identification results revealed that Lactobacillus gasseri was the predominant lactobacilli in healthy women. The amounts of lactic acid and by drogen peroxide (H2O2) produced by Lactobacillus spp. were determined. The vaginal pH levels induced by Lactobacillus spp. strains ranged from 1.00 to 2.15. The titratable acidity of the strains ranged from 0.27 to 1.33%. The H2O2 concentration produced in the lactobacilli strains ranged between 1.01 mu g/ml and 15.50 mu g/ml. The antimicrobial effects of the lactobacilli against the pathogenic bacteria Escherichia coli ATCC 11230, Staphylococcus aureus ATCC 2392, Pseudomonas aeruginosa ATCC 29212 and Salmonella enterica serovar Enteritidis RSKK 171 were also determined by the agar diffusion methods.