Sera from 95 women with cervical intraepithelial neoplasia (CIN), 95 age-matched female blood donors, and 155 children aged between 1 and 12 years were tested by enzyme-linked immunosorbent assay (ELISA) for levels of serum IgG to three human papillomavirus (HPV) peptides (HPV-16 E2 [E2-16], HPV-18 E2 (E2-18], HPV-16 L1 [L1-16]), as well as HPV-16 virus-like particles (VLP-16) and bovine papillomavirus type 1 virus-like particles (BPV-VLP). In the adult group antibodies to E2-16 and VLP-16 were significantly associated with CIN when compared to the blood donor controls (P = .039 and P = .002, respectively). In women with CIN there was an increase in seropositivity to E2-16 and a decrease in seropositivity to VLP-16 with age. Antibodies to HPV-16 E2 could therefore be an important marker of CIN in women over 40 years of age, whereas antibodies to VLP-16 could be a marker for CIN in younger women. There was no correlation with CIN and antibodies to E2-18, L1-16, and BPV-VLP. In the children's sera antibodies were detected to E2-16 (44.5%), E2-18 (18.7%), L1-16 (20%), VLP-16 (4.5%), and BPV-VLP (5.1%). Between the ages of 3 and 12 years the prevalence of antibodies to E2-16 decreased with age. The presence of antibodies to HPV-16 in young children indicated infection with either HPV-16 or a related virus. HPV DNA isolation from children could help resolve this question.