The incidence of vaginal intraepithelial neoplasia (VAIN) is increasing annually; however, the reported values are likely underestimated. Risk factors for VAIN include advanced age, human papillomavirus (HPV) infection, history of hysterectomy, and simultaneous or previous cervical intraepithelial neoplasia (CIN) or cervical cancer cervical cancer. The most common presentation is abnormal cytology without clinical symptoms. Despite various treatment modalities available, the rate of disease recurrence is high, and its malignant potential has been documented. This study aimed to examine demographic and clinical characteristics and associated treatment outcomes of patients with VAIN. We retrospectively reviewed clinicopathologic data and clinical outcomes of patients diagnosed with VAIN at a single center between January 2010 and December 2017. Overall, 118 patients were included (average age 49.81 ± 9.77 years; range, 26-70 years). The distribution of the histologic grade was as follows: VAIN1, 30.5%; VAIN2, 41.5%; and VAIN3, 28.0%. In total, 97 (82.2%) patients had either prior or simultaneous cervical lesions, CIN (35.6%), or cervical cancer (55, 46.6%). A total of 100 cases (84.7%) were diagnosed using colposcopy and 18 (15.3%) were diagnosed by pathological accident after hysterectomy. Thin-prep cytology test (TCT) results were available for 112 (94.9%) patients, and 111 (94.1%) patients had abnormal cytology findings. Most patients were confirmed as HPV positive (115, 97.5%), and 84 (71.2%) patients were confirmed as positive for high-risk HPV types. Forty-two (35.6%) patients underwent hysterectomy before VAIN diagnosis, and the median interval between hysterectomy and VAIN diagnosis was 26.5 (range: 3-68) months. Most surgical indications were HPV-related diseases (34, 80.9%), such as CIN (8, 19.0%) or cervical cancer (26, 61.9%). Eight patients had no history of cervical lesions. A total of 100 patients underwent initial treatment. During the median follow-up period of 29 (range: 9-96) months, 78 (78%) patients experienced disease remission after initial treatment, 7 (7%) experienced disease recurrence, 10 (10%) had persistent disease, and 5 (5%) had progressive disease. Finally, two patients developed vaginal cancer without death. Colposcopy should be performed before vaginal hysterectomy for VAIN, particularly HPV-related cases. The incidence of VAIN was 20% after hysterectomy owing to non-HPV-related lesions; thus, this part of the screening should not be discontinued. VAIN grade 2,3 and VAIN associated with CIN or cervical cancer are disease types more likely to recur and progress to invasive cancer; active medical intervention is recommended.