The risk of cervical neoplasia for women with normal Papanicolaou smears was calculated for those whose smears were human papillomavirus (HPV) positive and those whose smears were HPV negative. Data on 347 cases and controls were analyzed in a population-based, nested case-control study. Cases (n = 77) were women who participated in the Utrecht screening program (1976-1984) in the Netherlands and who developed cervical intraepithelial neoplasia 3 or microinvasive or invasive squamous cervical cancer after having a negative smear (1980-1986). Controls (n = 270) were matched on age (+/-5 years) and follow-up period. DNA was isolated from the Papanicolaou smears and was tested for the presence of HPV DNA by using the ultrasensitive broad-spectrum, general short-fragment polymerase chain reaction. HPV was found in 55 (71%) of the baseline smears of the 77 cases and in 31 (11%) of those of the 270 controls. The age-adjusted odds ratios for developing cervical intraepithelial neoplasia or microinvasive or invasive cervical cancer were 19.2 (95 percent confidence interval (CI): 10.3, 35.7) for HPV positivity in general, 5.4 (95% CI: 1.5, 19.5) for infection with low-risk HPV genotypes, 24.0 (95% CI: 12.4, 46.4) for high-risk HPV genotypes, and 104.8 (95% CI: 29.5, 372.7) for HPV type 16.