Objective To investigate the clinical characteristics,diagnosis and treatment of vaginal intraepithelial neoplasia(VAIN).Methods A retrospective study was made of 6 patients with VAIN.who were hospitalized at Peking Union Medical College Hospital from 1980 to 2006.Results Five cases had a history of hysterectomy,two of whom were because of cervical intraepithelial neoplasia(CIN)or invasive cervical cancer.Four cases had the infection of high-risk oncogenic human papillomaviruses detected with hybrid capture Ⅱ(HC-Ⅱ),the other two had no record.In all patients the VAIN lesions were within the upper one third of the vagina.They were all diagnosed by colposcopic examination and directed biopsy after the abnormal cytology by thinprep cytology test(TCT).Six cases of VAIN Ⅱ-Ⅲ were treated by excisional surgery.One case had residual lesion and had another surgery 3 months after the first one.Two patients obtained remission at one-year follow-up,three had abnormal cytology by TCT 6 months after surgery,and one had abnormal cytology by TCT at six-month follow-up but normal at one-year follow-up.Conclusions A history of CIN is the main risk factor for VAIN,so routine vaginal cytology is needed for the patients after hysterectomy due to CIN.Cytology,colposcopic examination and directed biopsy are the mainstays of VAIN diagnosis.Excisional surgery is recommended for the patients with VAIN Ⅱ-Ⅲ.Long term follow-up is necessary after treatment.