Primary cancers of the vagina are rare. They comprise 1% to 2% of all gynecologic malignancies and occur predominantly in older women. The diagnosis of primary carcinoma of the vagina requires that the cervix and vulva be intact and that no clinical evidence of other primary tumors exist. Approximately 90% of all vaginal tumors are squamous cell in type on histologic examination. Adenocarcinoma, which is much less common (2% to 4%), is seen primarily in younger women with in utero exposure to diethylstilbestrol. In addition to exposure to diethylstilbestrol, other environmental factors have been associated with the development of vaginal tumors, including chronic irritation from pessaries, previous hysterectomy for benign disease, immunosuppression therapy, cervical irradiation, and endometriosis. Infectious causes seem to play an even more pernicious role in vaginal cancer. The two agents most often implicated are herpes simplex virus and human papillomavirus. These viruses appear to serve as cofactors in the inducement of various genital cancers, working together or with environmental agents such as diethylstilbestrol and host-related genetic abnormalities. The prognosis of vaginal cancer depends on the stage of the disease, with an overall 5-year survival rate of 80% to 90% for early stages.