The pathogenesis of vulvar and cervical cancer are thought to be similar and to be related to a sexually transmitted agent, which, in recent years, has been demonstrated to be human papillomavirus. These two neoplasms differ dramatically in age distribution and relationship to precursor lesions, making a common etiology unlikely. The apparent discrepancies can be explained by a hypothesis that implicates human papillomavirus as an etiologic factor for the majority of cervical carcinomas but for only a small proportion of vulvar carcinomas. Most vulvar carcinomas occur in older women and are not related to human papillomavirus, whereas a subset of vulvar carcinomas occur in young women and are related to this virus. Characterization of two distinct types of vulvar carcinoma may clarify associated risk factors and may have important implications in the clinical management of this disease.