A new study published in the Chinese Journal of Epidemiology explored the effect of vaginal micro-environment alterations and human papillomavirus-16 (HPV16) infection and their interaction in the progression of cervical intraepithelial neoplasia. This study selected participants from the cervical lesions study cohort – 623 women with normal cervical (NC), 303 patients with pathogenically diagnosed low-grade cervical intraepithelial neoplasia (CIN I), and 93 patients with pathogenically diagnosed high-grade cervical intraepithelial neoplasia (CIN II/III). HPV16 infection were detected by using flow-through hybridization technology and H(2)O(2). The results showed that the HPV16 infection rate, pH, vaginal cleanliness, β-glucuronidase, and neuraminidase increased gradually along with the severity of cervical intraepithelial neoplasia, whereas the abnormal rates of clotting enzyme and leucocyte esterase did not. It was observed that there was interaction between HPV16 infection and abnormalities of H(2)O(2), β-glucuronidase, clotting enzyme and neuraminidase in CIN group, and the interaction between HPV16 infection and the abnormalities of vaginal cleanliness, H(2)O(2), β-glucuronidase and neuraminidase in CIN I/II group. Hence, it was concluded that the vaginal micro-environment alterations and HPV16 infection could increase the risk of cervical intraepithelial neoplasia. Furthermore, they might have an important synergistic effect in the progression of cervical intraepithelial neoplasia.