Vaginal swabs from 2715 consecutive unselected women with vaginal discharge were examined for Gardnerella vaginalis, Candida albicans and Trichomonas vaginalis. Of 2715 women, 2043 had non-specific vaginitis and G. vaginalis was isolated from 269 cases (13.2%). Thirty five of the strains were isolated together with C. albicans, eight with T. vaginalis, six with Bacteroides species and three each with group B Streptococcus and Staphylococcus aureus. Two hundred and sixteen (80%) of the isolates were from females between the age of 20 and 34. All 269 strains hydrolysed hippurate and fermented starch; 161 (60%) were isolated from swabs without clue cells. Although facts suggest that vaginal discharge in most of these cases had been associated with G. vaginalis, a possible aetiological role for other micro-organisms has not been ruled out. However, successful therapy with metronidazole in 80% of those cases suggests that G. vaginalis is one cause of non-specific vaginitis. The prevalence rate of G. vaginalis in 160 randomly selected women without vaginal discharge was 5%.