To test the hypothesis that all cases of vaginal candidiasis are associated with a "reservoir" of this organism in the bowel, paired specimens of feces and vaginal material were cultured for Candida albicans simultaneously. Ninety-eight young women who complained of recurrent vaginitis were selected in sequence. The results showed that if C albicans was cultured from the vagina, it was always found in the stool. Conversely, if it was not isolated from the stool, it was never found in the vagina. These data are presented as an explanation for the recurrent nature of Candida vaginitis, and thus a cure of vaginitis would not be possible without prior eradication of C albicans from the gut. The gut-reservoir concept may well apply to other forms of candidiasis.