Background: Vaginal intraepithelial neoplasia is a little known disease which could be related to risk factors different from simple HPV infections. Objective: To ascertain wheter vaginal lesions have a natural history similar to cervical lesions. Materials & Methods: A retrospective study to identify patients with vaginal lesions and synchronous cervical lesions through biopsy. The rate of mild cervical lesions (koilocytosis, warts, CIN I with and without koilocytosis) was compared with the rate of severe cervical lesions (CIN II and III, cervical carcinoma) in patients with mild vaginal lesions (warts and koilocytosis, and low-grade VAIN) and in patients with severe vaginal lesions (high-grade VAIN). Using koilocytosis as a marker, the rate of “active” cervical lesions was compared with the rate of “non active” cervical lesions in patients with “active” versus “non active” vaginal lesions. Finally, the rates of mild and severe cervical lesions were compared among each group of VAIN (low-grade, high-grade, with or without koilocytosis). Results: In patients with mild vaginal lesions, mild cervical lesions were significantly more frequent than severe cervical lesions. In patients with “active” vaginal lesions the rate of “active” cervical lesions was significantly higher than “non active” cervical lesions. The differences in rates of mild cervical lesions and severe cervical lesions among patients with high-grade VAIN and low-grade VAIN (with and without koilocytosis) were not significant. Conclusion: These data suggest that CIN and VAIN may have some common features in certain cases, i.e., if an HPV infection is proved.