We investigated neutralizing antibodies to human papillomavirus type 16 (HPV-16) in serum and cervical washes from 84 women with normal cytology or cervical disease. Serum neutralizing antibodies were detected in 78 % of women infected at the cervix with HPV-16, compared with 35 % (P=0.002) of women infected with HPV-16-related types (alpha9 HPV types), 14 % (P<0.0001) of women infected with HPV-16 non-related types and none of HPV-uninfected women. A significant correlation between HPV-16 infection and serum HPV-16-neutralizing antibodies was observed (r(s)=0.97; P=0.032). Cervical neutralizing antibodies were detected in 38 % of women with HPV-16 infection and in 17 % of women infected with the HPV-16-related type HPV-31. Cervical neutralizing antibodies correlated with HPV-16 infection (r(s)=0.95; P=0.08), but not with cervical disease. Serum and cervical HPV-16 antibody responses were not affected significantly by human immunodeficiency virus type 1 infection. In conclusion, serum and cervical HPV-16-neutralizing antibodies were found to correlate with HPV-16 infection, but not with cervical disease.