The goal of this study was to investigate the role of human papilloma virus (HPV) in the development of cervical neoplasia in women who had no previous diagnosis of cytological abnormalities. Participants were over 11,000 women aged 20 to 29 years, recruited from a population registry in Denmark from 1991 to 1993. Participants completed baseline assessment at recruitment and were followed up around two years later, from 1993 to 1995. Passive follow-up continued until 2007 through the Pathology Data Bank.