Genital infection with high-risk human papillomaviruses (HPV) has been etiologically linked with the development of cervical and other anogenital cancers. There is therefore a need for an effective HPV vaccine with the potential to significantly reduce the burden of more than half a million new cervical cancer cases in women worldwide each year. The LI major capsid protein of papillomaviruses expressed in eukaryotic cells self-assembles into virus-like particles (VLP). VLP are attractive subunit vaccine candidates since they lack potentially oncogenic papillomavirus DNA and express the conformationally dependent epitopes necessary to induce high-titer neutralizing antibodies. Prophylactic VLP vaccination has achieved a high degree of protection in animal studies. Thus VLP are now considered the immunogen of choice for human vaccine trials to prevent genital HPV infection. VLP of different HPV have been developed to study the serologic relationship between HPV types. VLP-based ELISA are able to detect antibodies in human sera and are now widely used in epidemiologic studies of the natural history of HPV infection and the associated risk of developing neoplasia.