Human papillomavirus (HPV) infection is a necessary cause of cervical cancer, and is etiologically associated with a subset of cancers of the anus, oropharynx, penis, vagina, and vulva. Current data indicate that HPV infection is potentially associated with 90%-93% of anal cancers, 12%-63% of oropharyngeal cancers, 36%-40% of penile cancers, 40%-64% of vaginal cancers, and 40%-51% of vulvar cancers. HPV infection accounts for up to 492,800 cervical cancers and 97,215 cases of noncervical HPV-related cancers worldwide during 2002, including up to 50,780 cancers among men (13,485 anal cancers, 26,775 oropharyngeal cancers, and 10,520 penile cancers) and up to 46,435 cancers among women (14,787 anal cancers, 6,048 oropharyngeal cancers, and 25,600 vaginal/vulvar cancers). In the United States annually (1998-2003), up to 10,846 cervical cancers, 4,753 noncervical cancers among men, and 4,128 noncervical cancers among women are potentially attributable to HPV infection. Incidence rates for cervical cancer have declined significantly during the past 30 years in the United States, consistent with the success of Pap smear screening. However, incidence rates for anal, oropharyngeal, and vulvar cancers have increased substantially in recent years. The high proportion of cervical and noncervical cancers caused by HPV types 16 and 18, that is, 70%-76% for cervical cancers and 63%-95% for noncervical cancers, underscores the potential for prevention of a majority of cervical as well as noncervical HPV-related cancers through prophylactic HPV vaccination.