Vaginal flora was studied quantitatively in 29 sexually active women, 16 to 33 years of age, to define the role of C. vaginale in vaginitis. Seventeen were asymptomatic and 12 complained of symptoms of vaginitis. Seven asymptomatic women had scant secretions: four of these seven had C. vaginale at log10 6 to 9 CFU per milliliter, none of whom had "clue" cells; none had trichomonas or candida; six had lactobacilli at log10 7 to 9.7 per milliliter; only one had Bacteroidaceae at greater than log10 5 per milliliter. Ten asymptomatic women had easily collectable secretions; eight of 10 had C. vaginale at log10 6.5 to 9.6 per milliliter, three of whom had "clue" cells; four had trichomonas and none candida; nine had Lactobacilli at log10 7 to 9.3 per milliliter; four had Bacteroidaceae at greater than log10 5 per milliliter. Twelve had vaginitis: five of 12 had C. vaginale at log10 7.9 to 11 per milliliter, one of whom had "clue" cells; nine had either trichomonas or candida or both and three had no pathogen, including C. vaginale; 10 had Lactobacilli at log10 7 to 10 per milliliter; six had Bacteriodaceae at greater than log10 5 per milliliter. Three had "clue" cells in absence of C. vaginale.