Gynecological diseases may affect the growth of vaginal bacterial flora. We investigated the relationship between uterine cervical cancer and the vaginal bacterial flora. In 20 patients with uterine cervical cancer, we investigated the intravaginal bacterial flora, including Gardnerella vaginalis and Mobiluncus spp. In the patients with uterine cervical cancer, there was a mixed flora of aerobes and anaerobes and, of special note, G. vaginalis was detected in 50% of the patients with uterine cervical cancer (10/20). Bacterial vaginosis was present in 8 of these 10 patients (80%). The count of G. vaginalis detected was higher than that of the other coexisting species and was higher in both pre- and postmenopausal patients with uterine cervical cancer than in a control group of pre- and postmenopausal women with benign gynecological diseases. In contrast, none of Mobiluncus spp. was detected. G. vaginalis was detected at a high incidence in patients with uterine cervical cancer, suggesting that the lesions of uterine cervical cancer provide favorable conditions for the growth of G. vaginalis and anaerobes, which leads to bacterial vaginosis.