Background: To evaluate the possible protector role of Lactobacillus against vaginal candidiasis. Patients and method: In vitro studies performed to assess the capacity of 15 Lactobacillus strains to block the adhesion of two Candida albicans and one C. glabrata strain to vaginal epithelial cells and to inhibit the growth of these yeasts. Moreover, the presence of Lactobacillus was analyzed in 115 vaginal exudates from women with vaginal candidiasis. Results: Only 8 of the 15 lactobacilli studied significantly blocked the adhesion of C. albicans Y18 to vaginal cells. Lactobacilli from group III showed the greatest blocking capacity (62.9%), followed by group II (50.6%) and group I (26.1%). In solid assays, none of the 15 Lactobacillus strains studied was able to inhibit growth of the 3 yeasts. However, in liquid assays some lactobacilli evidenced a certain degree of inhibitory power against C. albicans Y17 (35.7%, 41.7% and 38.1% of light transmittance for Lactobacillus groups I, II and III, respectively). Lactobacillus was detected in 89.6% of women with vaginal candidiasis (by microscopy in 87.8% and by culture in 72.2%). Conclusions: These results lead us to suggest that probably Lactobacillus provides protection against vaginal candidiasis.