Objective  To evaluate the effectiveness of live lactobacilli in combination with low dose oestriol for restoration of the vaginal flora after anti‐infective treatment. Design  The study was designed as a single centre, randomised, placebo‐controlled, double‐blind clinical trial. Setting  University Hospital. Sample  Three hundred and sixty women out of 1750 were randomised. Methods  Three hundred and sixty women with the complaints of vaginal infections (bacterial vaginosis, candidiasis, trichomoniasis or fluor vaginalis) were randomly assigned two to seven days after the end of the anti‐infective therapy, to therapy with live lactobacilli in combination with low dose oestriol (study group, n= 240) or placebo (n= 120). The follow up visits occurred three to seven days and four to six weeks after the end of the restoration therapy. Main outcome measures  The Normal Flora Index (NFI), which consists of numbers of lactobacilli, pathogenic microorganisms, leucocytes and vaginal pH, was used as the primary outcome of the study. Secondary outcomes included the total symptoms score, the degree of purity of the vaginal flora and the global assessment of the treatment by the investigator and the women. Results  During restoration therapy, the NFI increased significantly more in the study group than in the control group in both first and second control visits (P= 0.002 and P= 0.006, respectively). The degree of purity of the vaginal flora also increased significantly more in the study group compared with the control group (P < 0.0001 and P= 0.001, respectively). No serious adverse event was reported during restoration therapy. Conclusion  Restoration of the vaginal flora can be significantly enhanced by the administration of live lactobacilli in combination with low dose oestriol.