The pattern of spontaneous screening for cervical cancer by general practitioners and gynaecologists in The Netherlands is compared with an efficient screening policy resulting from a cost-effective study. Spontaneous screening tends to start and stop too early in a woman's life, and leaves too many women overscreened or unprotected. The combination in young age of a low incidence of invasive cancer and a high incidence of regressive lesions explains relative ineffectiveness and harmfulness of present screening practice. When screening would take place between ages 30 and at least 60, with intervals of about 5 years, as many lives could be saved for half the costs and with only 60% of the unnecessary referrals and treatments. Much attention should be paid to the coverage of the target population. Therapeutic follow-up policies for dysplastic lesions should be restrained.